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Using a Sigma 24mm F/1.4 for Astrophotography

|Camera Lenses|6 Comments

The Sigma 24mm F/1.4 lens is an interesting choice for astrophotography, particularly wide-angle Milky Way photography. With an f-ratio of F/1.4, this Sigma art series lens can pull in a lot of light under a dark night sky.

Over the years I have used a number of great camera lenses for astrophotography from the Rokinon 135mm F/2, to the Canon EF 300mm F/4L. The Sigma 24mm F/1.4 is perhaps the most impressive lens for astrophotography overall, rarely due to its incredibly fast aperture. 

I’ve used the lens on my Canon DSLR and Mirrorless cameras, and have found it to be one of the most useful lenses I own. The reviews on B&H Photo indicate that Nikon and Sony camera owners have had a positive experience with this lens as well.

The lens isn’t perfect, but it is an exceptional value and has impressive qualities that amateur astrophotographers can appreciate. The lack of image stabilization will likely be a deciding factor for those looking to use this lens for video work, but I have found it to be very useful when filming in low-light situations despite this feature. 

In this article, I will share my results using the Sigma 24mm F/1.4 Art lens for astrophotography. The photo shown below was captured using the Sigma 24mm F/1.4 lens and my Canon EOS Ra mirrorless camera.

The Milky Way

The Milky Way under a Dark Sky. Canon EOS Ra + Sigma 24mm F/1.4.

To create the image above, I capture multiple 90-second exposures on a portable star tracker (Sky-Watcher Star Adventurer). My wife and I rented an Airbnb at a dark sky location (Bortle Scale Class 3), to enjoy an unspoiled night sky. 

24mm is an ideal focal length for astrophotography applications, particularly nightscape photography. When paired with a full-frame astrophotography camera, the results are simply stunning. 

For the image above, my exposures were shot at ISO 3200 at F/2.8. Take a look at the example image below to see the difference between a single frame, and the final stacked image.

single exposure vs. stacked image

I have used the Sigma 24mm F/1.4 Art Lens on my full-frame Canon cameras for astrophotography. I have a Canon EOS 6D Mark II (stock), and a Canon EOS Ra (astrophotography) camera. 

The stock 6D II is used mainly for videography with the Sigma lens, while the EOS Ra is used for long-exposure night sky imaging exclusively. 

Sigma 24mm F/1.4 Art Lens

The Sigma 24mm f/1.4 Art lens is a professional-grade wide-angle lens part of the overall Art-series by Sigma, which are great budget-friendly alternatives to similar, and more expensive Canon, Nikon, and Sony lens options.

The lens I use includes the Canon EF-mount, which I can also use on my RF-mount Canon EOS Ra using a Canon EF – EOS R adapter

The 24mm lens is the second widest prime lens in the Sigma Art series, ideal for low-light photography. An aperture of f/1.4 is a very attractive spec for amateur astrophotographers that capture images and videos at night. This is lens is also suitable for many other types of photo/video work, such as weddings, landscape photography, and event photography.

One of the big selling features for me was the 77mm lens diameter, which allows me to utilize my existing collection of UV and ND filters. 

Sigma 24mm F/1.4 lens

The Sigma 24mm F/1.4 Art lens attached to my Canon EOS Ra Mirrorless body (using an adapter).

The Sigma 24mm F/1.4 offers impressive sharpness characteristics and offers an optical formula comprising 15 total elements in 11 groups, four of which are low dispersion, three that are low-dispersion (FLD), and two that are aspherical. The premium glass elements bring aberrations and distortion to a minimum, which is a common issue with many wide-angle lenses.

The focus ring, located on the front of the lens barrel, is very smooth and easy to rotate which is important for manual focusing. The lens focuses fast and is equipped with a high-quality hyper-sonic motor, found on other Sigma lenses, providing fast and quiet (i.e. barely audible) autofocus.

Like some of the other Sigma Art-series lenses, the 24mm f/1.4 Art, unfortunately, does not have a rubber gasket on the mount, meaning there is the risk of dust, moisture, and other debris to get between the lens and the camera mount. It is important to be mindful of this while using the lens to ensure the area is clean at all times.

While I did not experience any issues with auto-focus, others have indicated that they had auto-focus issues when shooting at wider apertures, which was solved by using a Sigma dock and some auto-focus adjustments.

Overall, the lens had low distortions, normal vignetting, fast/reliable auto-focus, pro-level build quality, and construction and is great in low-light situations. It is also considerably more affordable than other 24mm f/1.4 wide-angle lenses.

lens construction

The lens construction diagram of the Sigma 24mm F/1.4 Art lens. 

Sigma 24mm F/1.4 Art Complete Specs:

Focal Length: 24mm
Maximum Aperture: f/1.4
Minimum Aperture: f/16
Lens Mount: Canon EF
Format Compatibility: Full-Frame
Angle of View: 84.1°
Minimum Focus Distance: 9.84″ / 25 cm
Maximum Magnification: 0.19x
Optical Design: 15 Elements in 11 Groups
Diaphragm Blades: 9, Rounded
Focus Type: Autofocus
Image Stabilization: None
Filter Size: 77 mm (Front)
Dimensions: (ø x L) 3.35 x 3.55″ / 85 x 90.2 mm
Weight: 1.46 lb / 665 g

creative night sky photography

A creative shot with out-of-focus stars using the Sigma 24mm F/1.4 Art Lens. 13-seconds, ISO 400, F/1.4.

Uses in Astrophotography

Although I find the autofocus system on the Sigma 24mm F/1.4 to work exceptionally well in low-light video situations on my Canon EOS 6D Mark II, this feature is not used in my long-exposure imaging projects. That is because you must manually focus the lens on a bright star before taking the picture. Autofocus just won’t work pointed up at a dark night sky.

To focus the lens, I simply use the 10X live view mode on the camera’s display screen and find the brightest star in the field of view. It is best to use the maximum aperture (F/1.4) and a generous ISO setting (ISO 3200 or above) when focusing the lens on a star. Once you have it dialed in, you can stop the lens back down to F/2.8 or slower for a sharper image. 

Compared to other lenses I have used for Milky Way Photography, such as the Rokinon 14mm F/2.8, the Sigma 24mm F/1.4 is noticeably sharper at the edges of the frame. This is not surprising, as the Sigma is a higher-quality lens overall and not “ultra-wide-field” like the fully manual Rokinon. 

The following image was captured using the Sigma 24mm F/1.4 Art lens attached to my Canon EOS Ra and a Sky-Watcher Star Adventurer tracking mount. The image on the left is a single frame, while the one on the right is a processed stack of images to enhance color and clarity.

To learn how I process my astrophotography images, consider downloading my premium image processing guide

image processing

The Milky Way. Single Exposure vs. Processed Stack.

Clearly, the focal length of this lens lends itself well to capturing large portions of the night sky at once. With a crop-sensor camera, expect the field to be significantly reduced. To fully utilize the benefits of this lens, stick to full-frame camera. 

I enjoy the framing a 24mm focal length provides, but if you’re looking for something even wider, consider the Sigma 14mm F/1.8 Art Lens. The 14mm versions enters “ultra-wide” territory and would be a great fit for capturing the Milky Way, timelapses, meteor showers, and star-trail images.

There are a few secrets I would like to share about using the Sigma 24mm F/1.4 lens for astrophotography. These tips include techniques to apply in the field while shooting, as well as post-processing steps to take.

The first one is not such a big secret if you’re accustomed to processing astrophotography images in Adobe Photoshop.

Lens Profile Correction

I used the lens profile correction feature found inside of Adobe Camera Raw before stacking the images manually in Photoshop. The Sigma 24mm F/1.4 lens was recognized to have an associated profile in Adobe Camera Raw, as is the case for every lens I’ve ever used for astrophotography.

The main benefit of this technique is that it helps correct the curvature of the image that was evident in the RAW image files out of the camera. When comparing the image before and after the profile correction, I noticed that it flattens the field quite substantially.

lens profile correction

 I recommend applying the lens correction profile to all sub-exposure images before stacking, as opposed to a global application of the stacked/calibrated final. You can easily copy and paste your develop settings in Adobe Camera Raw and “paste” them to all of the images in the folder.

 This technique also helps to reduce any chromatic aberration of the stars in the image, which is a huge bonus.

Correcting color fringing in the image processing workflow is a standard procedure, but it certainly helps to apply a specific lens profile to the data at the onset.

Focusing the Lens

The Sigma 24mm F/1.4 has an impressive autofocus system, even when using the lens at its maximum aperture of F/1.4. This, of course, is in the daytime. For all astrophotography purposes (including video work), I use manual focus on this lens.

For daytime (and even dusk) filming on my Canon EOS 6D Mk II, the continuous autofocus capabilities of this lens are a lifesaver. I can simply tap the flip-out LCD screen to refocus on my face or any equipment I happen to be talking about.

However, at night, all of this goes out the window and the lens will not focus on stars in the night sky. For photography purposes, I simply use the manual focus ring to achieve a tight focus on the stars in the night sky.

For most lenses, it is best to “stop down” the lens for a sharper image. You will lose light-gathering power, of course, but your stars will likely look better at a slower f-ratio. On the Sigma 24mm F/1.4 Art lens, I find F/2.8 to be a good balance between aperture and image quality. 

Advice When Stacking Images

Depending on the way your individual sub-exposures were captured, you may notice some rotation in your final stacked image. This can be very difficult to overcome, but I believe that applying the lens profile to your sub-exposures before stacking will help. 

For nightscape astrophotography, I like to use Sequator to stack my images. This is a simple, free software that allows you to improve the signal-to-noise ratio of your final image by integrating several exposures together. 

This program allows you to select the areas of your image you would like the stack (such as the stars), and the areas you wish to leave alone (the landscape). It’s not perfect, but with some trial and error, you may find it to be a useful tool for your nightscape photos. 

I prefer to keep the default setting applied for the most part. I do not utilize the auto-brightness, high dynamic range, reduce light pollution, or enhance star light options, but you may want to try those settings out on your image.

Sequator Image Stacking

Stacking images in Sequator.

There are a few challenges that may arise when attempting to stack your individual light frames in Sequator (or DeepSkyStacker for that matter). The issues are not exclusive to camera lens astrophotography, but you will need to keep them in mind when taking photos with the Sigma 24mm F/1.4 Art Lens. 

Some tips for anyone looking to use the Sigma 24mm F/1.4 DG HSM Art lens for astrophotography are:

  • Capture long-exposure images (30-seconds +) on a star tracker mount
  • Capture a series of exposures to stack using software such as Sequator or DeepSkyStacker
  • Stop the lens down to F/2 or slower for sharper stars, especially near the edges of the frame
  • Use a bright star to manually focus the lens before capturing your subject
  • Capture your stationary foreground details in a separate exposure and blend with your stacked/tracked images

Milky Way astrophotography

The Milky Way. 10 x 30-seconds using the Sigma 24mm F/1.4 and Canon EOS Ra. 

The Bottom Line

The Sigma 24mm F/1.4 Art lens was a welcome addition to my ever-growing line-up of lenses for astrophotography. It is my fastest lens I own, at a convenient focal length for most projects. 

A “nifty-fifty” (50mm, F/1.8) lens is comparable, but I find a 50mm to be a bit too long when you want to capture a large area of the night sky in a single shot. However, an entry 50mm lens will get you the light-gathering power at a much more affordable price. 

The Sigma Art Series of lenses offer impressive quality and are a great value, and the astrophotography community seems to agree on this. 

In my experiences with the Sigma 24mm F/1.4, the images are impressively sharp and flat when paired with my full-frame Canon DSLR and Mirrorless cameras. I usually stop the lens down to F/2.8, but getting creative at F/1.4 can be useful for certain projects as well. 

For video work, this lens is quiet and focuses quickly (with adequate lighting). I have used this lens for the majority of my YouTube videos in 2020. If you notice scenes that include stars and constellations in the night sky, the Sigma 24mm F/1.4 was used. 

Sigma lens bokeh

The beautiful lens bokeh of the Sigma 24mm F/1.4 wide open. 

The Sigma Art Series Lens Line-up

The Art Series lenses are available for Canon, Nikon, and Sony camera bodies. The “DG” in the name stands for “digital full-frame and APS-C”, and the “HSM” stands for “hyper-sonic motor”. 

Here are the lenses I believe most astrophotographers and nightscape photographers will be interested in:

  • 14mm F/1.8 DG HSM
  • 20mm F/1.4 DG HSM
  • 24mm F/1.4 DG HSM
  • 28mm F/1.4 DG HSM
  • 30mm F/1.4 DC HSM
  • 35mm F/1.4 DG HSM
  • 35mm F/1.2 DG DN
  • 40mm F/1.4 DG HSM
  • 50mm F/1.4 DG HSM

Sigma offers Art series lenses beyond 50mm (including an enticing 50-100mm zoom lens). I am looking into the 14mm F/1.8 as an alternative ultra-wide-angle lens. The 35mm F/1.2 Art lens is the fastest lens of the bunch but is currently only available for Sony camera bodies. 

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Canon EOS Ra Review

|Camera|18 Comments

The Canon EOS Ra camera is Canon’s first full-frame mirrorless camera dedicated to astrophotography. It is suitable for deep-sky imaging with a telescope, and night sky photography with a camera lens.

Based off of the extremely popular EOS R, the EOS Ra boasts unique features such as 30x magnification (viewfinder and Live View) for precise focusing, and roughly 4x more transmission sensitivity to the hydrogen-alpha (Hα) wavelength.

  • Name: Canon EOS Ra
  • Based on: Canon EOS R
  • Release Date: November 2019
  • Type: Mirrorless System
  • Resolution: 30.3 MP
  • Sensor size: Full-Frame
  • Sensor type: CMOS (specialized IR filter)
  • Lens Mount: Canon RF
  • Features: 30X Live View, Vari-angle LCD touchscreen

In the following video, I share my results using the Canon EOS Ra camera attached to a small telescope. This camera is suitable for high-resolution deep-sky astrophotography using a variety of optical instruments.

Canon EOS Ra Review

In late December 2019, Canon USA reached out to me to test their new astrophotography camera, the Canon EOS Ra. The “a” in the name of this camera stands for astrophotography.

That is because, unlike the regular Canon EOS R, this camera is 4X more sensitive to the h-alpha wavelength of the visible spectrum (656.3 nm). This helps collect the important deep red hues of many nebulae in the night sky. 

As Canon puts it, positioned in front of the CMOS imaging sensor, The EOS Ra’s infrared-cutting filter is modified to permit approximately 4x as much transmission of hydrogen-alpha rays at the 656nm wavelength, vs. standard EOS R cameras.” 

Canon EOS Ra Astrophotography

The North America Nebula. 5+ Hour Exposure Using the Canon EOS Ra.

The Canon EOS Ra also includes astrophotography-friendly features such as a unique 30X live-view mode on the vari-angle touchscreen LCD display screen. It’s a color astrophotography camera that was intended to be used for both deep-sky astrophotography, and wide-angle nightscapes.

In this article, I will review the Canon EOS Ra from the perspective of an “ordinary” amateur backyard deep-sky astrophotography enthusiast. As with every review I post, I was not compensated to endorse the product in any way. All of my opinions about this camera are my own. 

Before using the EOS Ra for astrophotography, I previously enjoyed using Canon’s last astrophotography camera, the (APS-C sensor) Canon EOS 60Da DSLR. The EOS Ra, on the other hand, is a full-frame mirrorless camera. 

Canon EOS Ra body

The Canon EOS Ra is a full-frame mirrorless astrophotography camera that is capable of producing APOD worthy astrophotography images. It is not a “one-trick-pony”, so to speak, as many of the other options available to amateurs are. Not only can the Ra take incredible deep-sky images through a telescope, but also using a wide variety of lenses, and without computer control. 

Having a camera with a long-lasting internal battery and a touchscreen display means that you are able to make adjustments to your exposures and key settings on the fly. You do not rely on third-party software to run this camera, although it can be used with popular software such as Astro Photography Tool, or Canon EOS Utilities.

The tactile experience of the EOS Ra camera body inspires you to focus on creative photography that excites you, and less on micro-adjustments and graphs on a computer screen. To be perfectly honest, the Canon EOS Ra is just more fun to use than any other astrophotography camera I’ve experienced. 

Orion Nebula using the EOS Ra

The Orion Nebula using the Canon EOS Ra (40 x 4-minutes at ISO 800).

Camera Features

At the heart of the Canon EOS Ra, is a 30.2 megapixel full-frame CMOS sensor. That’s a massive 36 x 24mm sensor, an uncommonly large size in the realm of astrophotography cameras.

This translates into an extremely wide field of view when used with a compact refractor telescope. It utilizes the native focal length of the optical instrument rather than cropping the image as smaller sensors do. 

So, if you use a telescope like the Sky-Watcher Esprit 100, you are shooting at the listed focal length of 550mm. This determines the magnification of the deep-sky object and the resolution of your image. 

The EOS Ra includes all of the advanced features of the EOS R, including a self-cleaning sensor unit, dust delete data function, and an OLED color electronic viewfinder

Canon EOS Ra box

Through this viewfinder, you can monitor key camera settings including exposure information, battery level, ISO speed, histogram, white balance, and much more. 

Bluetooth and WiFi connectivity are standard features of the EOS Ra, too. Does your dedicated astronomy camera offer this? 

 The Canon EOS Ra includes Dual Pixel CMOS autofocus. This advanced focusing system found in the original EOS R will not be utilized in many astrophotography-related shoots, but for video work, AF modes like Face+Tracking are incredibly useful. 

Canon EOS Ra camera body

Specifications

  • Format: Full-Frame
  • Sensor Type: CMOS
  • Sensor Size: 36 x 24mm
  • Pixel Size: 5.36 microns
  • Max. Resolution: 6720 x 4480 (30.2 MP) 
  • ISO Sensitivity: 100 – 40000
  • Lens Mount: Canon RF
  • Video Modes: 4K up to 30p, HD up to 60p
  • Memory Card: Single SD
  • Weight: 1.45 lbs.

When comparing the price of the Canon EOS Ra to a dedicated astronomy camera, consider the sheer amount of features this camera has that the latter does not (onboard touch-screen LCD, WiFi, 4K video, dual pixel AF, etc.). Will you use all of these advanced features for deep-sky astrophotography through a telescope? Probably not.

But the Canon EOS Ra is a multi-function camera that was designed to meet the needs of a broad range of amateur astrophotographers from wide-angle nightscape shooters to prime focus deep-sky imagers.

RF Lens Mount

The Canon EOS Ra features the new Canon RF lens mount, which allows you to use the latest RF mount lenses from Canon including the RF 85mm F/1.2L. If you already own Canon glass with the EF lens mount system, you simply need to use the EF-EOS R lens mount adapter to attach them to the EOS Ra.

Yes, the adapter is an added expense to use your existing Canon glass, but you will now be able to experience the impressive RF Lenses available. According to Canonwatch.com, the RF lenses are an improvement over their EF counterparts, as shown in the DxOMark testing (at least on the RF 50mm F/1.2L lens).  

RF - EOS R lens mount adapter

The Canon EF – EOS R lens mount adapter for EF-mount lenses. 

Canon EOS Ra review

Canon EOS Ra with RF 85mm F/1.2L lens attached.

I won’t go too into detail about the 85mm F/1.2 lens Canon included with the EOS Ra for my testing, but an 85mm prime is certainly an attractive focal length for astrophotographers. In terms of deep-sky imaging, this lens is best enjoyed under dark skies rather than an orange-zone backyard in the city.

Test Images using the 85mm F/1.2 Lens

I had a brief opportunity to test the Canon RF 85mm F/1.2 under semi-dark skies (Bortle Scale Class 5) on a moonless night. The photo I captured that night (watch the video) was really nothing special, until you realize that it was accomplished in about 10 minutes. 

Nightscape photographers with access to a dark sky site and enough time will capture amazing images with the EOS Ra this spring. Milky Way season should be very interesting. 

nightscape photography example

The Heart and Soul Nebulae, and the Double Cluster in Perseus. 10 x 30-seconds at ISO 800. 

The image quality of the photos taken using the EOS Ra and 85mm F/1.2L lens was impressive. Each exposure was 30-seconds long, and the noise was minimal despite using ISO 800. 

The following example image shows the star quality you can expect using this lens at F/1.6, and it is quite impressive if you ask me. Only the top corners show stars that are not absolute pin-points, which is admirable considering the monster-sized image sensor of this mirrorless camera. 

Image quality

Click the image for a large version of the image to inspect the star quality.

New RAW Image Format

The Canon EOS Ra shoots RAW images in .CR3 format. This slight number change (from the previous .CR2 format of Canon DSLR cameras) is actually a big deal. All of the software you use for registration, calibration, and image editing must be able to work with this new file format. 

For example, the pre-processing software I use (DeepSkyStacker) accepts .CR2 RAW image files, but not .CR3. That means that I must convert the native RAW image format from the Canon EOS Ra to a .TIF file for the application to recognize it. 

Adobe Photoshop 2020 has no trouble opening up the .CR3 files in Adobe Camera Raw or Bridge (or Lightroom for that matter), but I still use DeepSkyStacker for the registration and calibration stages of my images. 

CR3 format

The .CR3 RAW image format is not yet supported by popular stacking software like DeepSkyStacker.

This adds additional time to the processing stages of astrophotography, and I hope that the software available at the time of writing “catches up” to the new image format. PixInsight users will also need to wait for LibRaw to support CR3 files to integrate data (the PixInsight RAW format support module uses LibRaw as a back-end to support digital camera raw formats). 

A potential workaround for this matter is to register all of your exposures in Adobe Photoshop, but I am unaware of a way to calibrate images with dark frames or flat frames using this method. 

Full Frame CMOS Sensor

The full-frame CMOS hydrogen-alpha sensitive sensor is likely the biggest appeal of the camera overall. If you want to shoot using the field-of-view you are accustomed to with a crop-sensor camera body, you have the option of switching to “crop” mode in the settings. 

Until now, the only full-frame camera sensors I had ever used for astrophotography were the Canon EOS 5D Mark II, and the Canon EOS 6D Mark II. Both of these camera bodies, however, were stock. 

With the EOS Ra, I was finally able to utilize the large image circles of my apochromatic refractor telescopes like the William Optics RedCat 51 and Radian Raptor 61.

You can manually change the cropping/aspect ratio of the image in the camera settings if desired. Most photographers will simply leave the camera in “FULL” (full-frame) mode, but the option of capturing images at a 1.6X (crop-sensor), 1:1, 4:3, or even 16:9 is there.

image crop

Setting the Cropping/Aspect Ratio on-camera.

A full-frame (6720 x 4480 pixel) sensor demands a flat field and large image circle, which should be kept in mind when considering the EOS Ra. If your optical instrument does not have an image circle large enough to accommodate the large sensor, you could always manually set the crop factor on the camera as shown above.

Key Camera Settings

For those using the EOS Ra for astrophotography, there are a few essential camera settings to remember. The most important, in my opinion, is to turn off the built-in long exposure noise reduction and the high ISO noise reduction.

This is a hot topic with amateur astrophotographers and night photographers, as some nightscape shooters that process single exposures may prefer it. For deep-sky imagers that stack multiple exposures, however, you will not want the camera to do any noise reduction before you integrate the data.

If you’re looking for a reliable way to reduce noise in your astrophotos, I recommend giving the Topaz Labs DeNoise AI software a try. 

camera settings

Most astrophotographers will want to turn off long exposure noise reduction and high ISO speed NR.

The other important setting to remember is to ensure you have enabled the setting that allows the camera to take an exposure without a lens attached. When you have connected the EOS Ra to a telescope, it will not recognize that the optical tube is acting as a lens. The feature can be found in the custom settings menu, and it is called Enable Release Shutter w/o lens.

For a detailed look at all of the features this camera includes, you have the option of spending a weekend reading the EOS R Advanced User Guide

Imaging Sessions and Results

If you are like me, a typical astrophotography imaging session will vary in length depending on the amount of clear sky time available. Some sessions last less than an hour due to incoming clouds. The EOS Ra excels in these situations, as a quick setup process is one of its specialties.

The Canon EOS Ra includes a feature I have never experienced before, one that allows you to take exposures longer than 30-seconds in bulb mode. This is something amateur astrophotography enthusiasts can appreciate, especially when using this camera with a portable star tracker such as the Sky-Watcher Star Adventurer, or iOptron SkyGuider Pro. 

Being able to quickly set up the Canon EOS Ra and a wide-field lens on a small star tracker means that you can enjoy spur-of-the-moment astrophotography sessions while traveling. For me, this means being able to escape the light pollution from home and bring the kit to a dark sky site. 

Canon RF 85mm F/1.2

The Canon EOS Ra mounted to a Sky-Watcher Star Adventurer at the side of the road.

I find that camera lenses of all focal lengths are best used under dark skies. The wide-field nature of most camera lenses can create challenging image processing scenarios under light-polluted skies, especially if no light pollution filter is used.

Gradients in the night sky due to the glow of the city can make it very difficult to neutralize the background sky across large areas. That is not to say that it isn’t possible to correct harsh gradients due to light pollution in Photoshop, but it can be very time consuming to achieve a natural result. 

The best remedy for this scenario is to try and reserve your wide-field, camera lens astrophotography for dark sky excursions during the new moon phase. 

Deep-Sky Imaging Through a Telescope

If you want to watch me experience the thrill of unboxing the EOS Ra for the first time, and some backstory behind my image of the Orion Nebula shared at the top of this post, feel free to watch the following video. If my music selection or the sound of my voice annoys you to no end, read on.

For many people using the Ra for astrophotography, you will be capturing a sequence of long-exposure images through a telescope (Here are the ones I recommend). This is standard practice for creating images with a strong signal-to-noise ratio. 

But to do this, you will need to expose your images for longer than 30-seconds, and automate the process to maximize your time under the stars. You have a few options here, including a remote shutter release cable, third-party acquisition software, or using the handy standalone feature on the EOS Ra mentioned above.

The EOS Ra includes a USB Type-C input connection (this is the cable you’ll want), which allows you to control the camera from your computer if desired. You can also run a sequence of exposures using a remote shutter release cable. I was delighted to see that the remote shutter cable input was the same one used on my Canon EOS Rebel DSLR’s. 

deep sky astrophotography

Using Astro Photography Tool (APT) to run an imaging session with the Canon EOS Ra.

For my deep-sky imaging sessions attached to a telescope, I chose to use Astro Photography Tool (APT) to run my deep-sky imaging sessions with the EOS Ra. The camera was recognized by the latest edition of APT (as a Canon EOS R), which meant I could use the software to help focus the camera and telescope, present a live-view image, and set a sequence of long-exposure images. 

The CMOS sensor of the EOS Ra is so sensitive using high ISO’s, that the live-view image mirrored the experience of a dedicated astronomy camera. Dim stars, bright nebulae, and galaxies appear in real-time. This makes finding and framing deep-space targets much easier at the beginning of your session.

Focusing with 30X Live View

Focusing the Canon EOS Ra on dim stars is easier than with any DSLR I have used in the past. This is largely due to the new 30X live-view mode, which allows me to really look closely at how tight the stars are. 

When using a Bahtinov mask, the process is even more precise as you can see the subtle changes in the central diffraction spike as you focus in and out in real-time. The vari-angle display screen makes it easy to tilt the display to a comfortable angle when the telescope is pointed upwards. 

The touchscreen means that you can quickly scroll across the frame with a finger swipe to find more stars or your deep-sky target in the field. I found the focusing experience on the camera body itself to be almost as practical as feeding the information to my computer screen using camera control software. 

Wide-angle nightscapes shooters or deep-sky astrophotographers running their imaging sessions on-camera will benefit most from this feature.

focusing with a telescope

4K Video at 30 FPS

One of the features many people like to ignore when complaining about how expensive this camera is, is the 4K 30 fps video mode. That’s stunningly high-resolution video footage from a full-frame mirrorless sensor.

Is this feature much less likely to be used by astrophotography enthusiasts? Perhaps. Being somewhat of a videographer myself (I have filmed and edited over 100 videos on YouTube), I consider this to be an exciting option – and what I would put to good use.

In fact, I tested the Canon EOS Ra’s video abilities for some daytime filming for one of my videos. I was quite astonished to observe that the colors were not far off of a “normal-looking” scene despite having nearly 4x the sensitivity to H-Alpha over a standard EOS R.

Surely a natural color correction could be achieved in post, especially if the video is shot in a neutral/flat color profile. The EOS Ra includes a handy color temperature compensation feature that corrects the images/videos’ current white balance setting. The adjustment settings are a blue/amber bias, or magenta/green bias with 9 levels of control for each.

EOS Ra 4K video mode

The Canon EOS Ra is a capable video camera with impressive options.

There are a staggering amount of video recording options on this camera, maxing out at 30P shooting in 4K (ALL-I compression). The most practical choice for my style of filming and editing is to shoot in 4K at 23.97 FPS in IPB format.

Shooting at 4K in ALL-I format demands a lot of CPU power and RAM to edit.

Attaching the EOS Ra to a Telescope

For anyone that has ever attached a DSLR camera to a telescope using a t-ring and an adapter, you’ll just need the RF to EOS R lens mount adapter to connect the Ra to a telescope.

This provides the right spacing needed between the camera sensor of the Ra and your field flattener/reducer. You simply thread your existing t-ring to the EF-EOS R adapter and attach the camera as you normally would.

This was the exact configuration I used when I attached the Canon EOS Ra to the field flattener of a William Optics Fluorostar 132 refractor. As you may be able to tell from the photo, the lens mount adapter adds the exact right amount of spacing between the CMOS sensor inside of the mirrorless camera body, and the glass element of the flattener/reducer.

attach EOS Ra to telescope

The EOS Ra attached to the field flattener of my telescope using the RF-EOS-R adapter and a Canon t-ring. 

I also attached the Ra to a smaller refractor, the William Optics RedCat 51. This was a promising imaging combination for wide-field projects. This telescope offers an incredibly wide 250mm focal length and utilizes the glorious full-frame sensor of the Ra. 

My favorite aspect of this setup, however, was how simple it was to put together and start imaging. This is the type of imaging kit that would be perfect for deep-sky astrophotography while traveling. 

mirrorless camera and telescope

The Canon EOS Ra attaches to the RedCat 51 easily using the EF – EOS R adapter and Canon T-Ring.  

Using Filters with the EOS Ra

If you are planning on using a filter with the Canon EOS Ra, there are limited options available. Astronomik offers a CLS filter (city light suppression) for the Canon EOS R (and Ra) in a clip-format. I was not aware of this broadband light pollution filter until it was brought to my attention in the comments section of this article (thank you)! 

The great thing about body-mounted filters is the option of using them with a camera lens attached. It also comes in handy in telescope configurations where there is no convenient location for a threaded filter. 

Astronomik EOS Ra filter

The Astronomik CLS XL-Clip Filter for EOS R Bodies. 

For a wide variety of filter choices (such as narrowband filters), try using a 2″ round mounted filter in the t-ring adapter or field flattener if possible.

The first image I captured using this camera through a telescope did not use a filter in place of the sensor. There was no practical location for any of my 2″ filters within the imaging train. 

The second time around, however, I was able to thread a 48mm round mounted filter to the inside of the camera adapter of the William Optics RedCat 51 (Optolong L-eNhance). 

Optolong L-eNhance

Astrophotography Results

When it comes to testing cameras, I often get an overwhelming feeling of “imposter syndrome”. I am not a professional photographer by any means, and my test images often leave a lot of room for improvement. I partially blame the imaging conditions I shoot in, which regularly include high clouds and a lot of moisture, on a good night.

Regardless, I like to think that I make the most of my situation. The images I take from my Bortle Scale Class 6/7 backyard are a realistic example of what you can expect. Here is an image captured using the Canon EOS Ra and a small refractor telescope (William Optics RedCat 51).  

Canon EOS Ra example image

The Flaming Star Nebula and Tadpole Nebula in Auriga. Canon EOS Ra and 51mm refractor. 

Image Details:

  • Total Exposure: 2 Hours, 30 Minutes (50 x 3-minutes)
  • ISO: 1600
  • White Balance: Auto
  • Filter: Optolong L-eNhance
  • Telescope: William Optics RedCat 51
  • Stacking and Calibration: DeepSkyStacker
  • Processing: Adobe Photoshop 2020

The image of the Flaming Star Nebula region shown above was captured on a night of average seeing, with a 25% illuminated moon present. The filter used was a dual bandpass filter that helps isolates the light emitted in the hydrogen-alpha and oxygen wavelengths of the visible spectrum. 

You can see this image in higher resolution on AstroBin. For a complete breakdown of the way I process my astrophotography images, consider downloading my image processing guide

Noise Performance

It is no surprise that many people would like to know how the Canon EOS Ra handles noise, particularly when using higher ISO values of ISO 800 or more. This camera is not cooled, which means that it is subject to thermal noise due to a warm ambient temperature.

All of my testing with this camera took place during a Canadian winter, so the camera never really got above 5-10 degrees Celcius. However, even under these conditions, the noise performance seemed better than that of my Canon EOS 60Da.

Here is a test image for you to review up close (click on the image). You’ll notice that the noise is minimal in a single 3-minute exposure at ISO 800. Furthermore, this noise is reduced significantly through image stacking.

ISO noise performance

I do not see noise being a problem in the warmer months with this camera, as long as you stack your images to improve the signal to noise ratio. 

Alan Dyer (in this Sky and Telescope article) reported that when using the Canon EOS Ra with higher ISO levels, it exhibits noise that is as good as, if not slightly lower than Canon’s 6D MkII (despite the 6D Mark II’s larger pixels). 

Final Thoughts

The Canon EOS Ra stole my heart from the very moment I revealed the California Nebula on the astrophotography-themed box. In the past, I have professed my love for Canon’s astrophotography cameras such as the Canon EOS 60Da. 

The experience I have had with the EOS Ra was full of memorable moments under the stars. The type of astrophotography that this camera inspires reminds me of why I got into this crazy hobby in the first place.

Now, I have not experienced Nikon’s full-frame astrophotography camera (the D810A DSLR), nor have I ever used a full-frame mirrorless camera from Sony such as the popular A7. So take that for what it’s worth, this is not a detailed comparison between competing cameras in this category.

EOS R for astrophotography

The only negative aspects of the camera I have found are that the large full-frame sensor can result in substantial vignetting with certain optical systems, and the lack of compatibility in certain software to the new .CR3 file format. If you own a telescope that does not feature an image circle designed for full-frame cameras, you will need to crop your images.

Hopefully, DeepSkyStacker will update soon with the ability to stack, register, and calibrate .CR3 RAW images. Other third-party applications will need to support this file type too, for the best overall experience with the Ra.

The Adobe DNG Converter is a great workaround for the time being, as this tool converts all of the files quickly. DeepSkyStacker accepts Raw DNG files, and you can integrate your data as you normally would. 

Adobe DNG converter

Use the Adobe DNG Converter to create Raw files that DeepSkyStacker will recognize.

All in all, the EOS Ra is a monumental step up from Canon’s previous astrophotography inspired camera. Fans of the DSLR/Mirrorless camera experience (especially if you own existing Canon glass), will adore the EOS Ra. I purchased my Canon EOS Ra at B&H Photo Video

what's in the box

Related Post:

Is the Canon EOS Ra Worth the Money?

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Sky-Watcher EQ8-R Pro (First Impressions)

|Equipment|22 Comments

A few weeks ago, I was lucky enough to receive a very large package in the mail, the Sky-Watcher EQ8-R Pro. Some people get excited about the arrival of flowers or perhaps a new book from Amazon at their door.

Me? I prefer over 100 pounds of deep-sky astrophotography equipment.

The brand new EQ8-R Pro is an observatory-class equatorial telescope mount capable of handing advanced astrophotography equipment, and one of the heaviest objects I have ever attempted to lift on my own. I’d like to think that deadlifting the heaviest of astronomy equipment is something I’ll always be able to do, but that is sadly not true.

Whirlpool Galaxy

My image of the Whirlpool Galaxy captured using the EQ8-R Pro mount.

I believe that most folks interested in an equatorial mount with this level of competence will be installing it in a permanent backyard observatory. As many of you know, I continue to haul all of my astrophotography in and out of the garage each and every time I set up.

Before I share any more down-to-earth amateur astrophotographer problems with you, I feel that it is important to let you know exactly how and why an unreleased Sky-Watcher EQ8-R Pro computerized GoTo mount was delivered to me.

Why I Do I Have One?

The team at Sky-Watcher wanted someone to review the EQ8-R Pro mount in a “real world” situation, and my light-polluted backyard in the city fit the bill quite nicely. To be quite honest, I did not have a need for a computerized GoTo telescope mount this large, but I am always happy to try out new equipment to better understand this hobby overall.

I have developed a great relationship with Sky-Watcher USA over the past year, and feel very comfortable demoing new products on my YouTube channel and website. This would not be the case if there were strict guidelines about what I can, or can’t say about the equipment, and I am happy to report, that there aren’t!

Despite what others have said in the forums, I have not “sold out” (a recent Cloudy Nights forum thread attacked my integrity), and earning my income by convincing someone to purchase a product or service I don’t believe in is exactly the type of scenario I removed from my life the moment I took on AstroBackyard full-time. 

Sky-Watcher

Sorry for the mini-rant, but I felt that this was important to mention moving forward. There’s bound to be skeptics in all disciplines, but the cost and potential frustrations involved with astrophotography gear can either bring out the best, or worst of us. 

To make things even more interesting, I’ve mounted a Sky-Watcher Esprit 150 Apochromatic Refractor and Starlight Xpress monochrome camera to the EQ8-R Pro. Sky-Watcher offers this imaging configuration as a package, and I believe you could call this one a “backyard astrophotographers dream”. I think now is a great time to remind you that my time with this setup is limited.

As with all of the equipment I review on AstroBackyard and on YouTube, I was not paid to endorse this product, and it will be returned to the company after my review. While this “dream setup” is available to me, you can bet your biscuit I am going to spend every second of clear sky collecting photons with it. 

equatorial telescope mount

The Sky-Watcher EQ8-R EQ can handle 110-pounds of equipment.  

The Sky-Watcher EQ8-R Pro 

The Sky-Watcher EQ8-R Pro (and Rh versions) officially launched on October 18th, 2019, almost exactly a year after I received my EQ6-R Pro (this mounts younger sibling). This robust equatorial telescope mount boasts an impressive 50 Kg (110-pound) maximum payload capacity, a belt-drive system on both axes, an integrated cable management system, and more. Despite these useful traits and advanced features, I like to think of the EQ8-R Pro as a big, black EQ6-R Pro, and that’s a good thing. 

After nearly a year of use and countless astrophotography images later, I reviewed the Sky-Watcher EQ6-R Pro. I had a wonderful experience with this mount, and judging from the comments I received on this blog and social media, others did too. 

I am a big fan of the Sky-Watcher SynScan system, as I regularly still use and enjoy the hand controller on my astrophotography mounts. I’ve used the Celestron NexStar and iOptron Go2Nova hand controllers in the past, but I am most comfortable with Sky-Watcher mounts thanks to over 5 years of experience using them (starting with the Sky-Watcher HEQ5 in 2014).

hand controller

The Auto Slew Home command appears when you turn the EQ8-R Pro on. 

First Impressions

It was refreshingly simple and straight forward to get the EQ8-R Pro aligned and tracking my desired astrophotography subjects. With a careful polar alignment using the QHY PoleMaster, a 1-star alignment was all I needed to center my target using a telescope with a 1000mm+ focal length. Astonishingly, I’ve actually kept and stacked every single exposure taken on the EQ8-R Pro mount since it’s been in the backyard.

I used Astro Photography Tool to automate my imaging sequence with the Starlight Xpress SX42 camera and utilized the autoguiding port on the EQ8-R Pro for accurate 5-minute exposures. The Starlight Xpress filter wheel contained 6nm Astronomik narrowband filters, Ha, OIII, and SII. I am certainly not used to capturing images at a focal length of 1000mm, so I couldn’t help but get a closer look at some of the nebulae I’ve had a hard time reaching with my wide-field setups. 

Here is an image of the Bubble Nebula captured using the Esprit 150 refractor of the EQ8-R Pro:

Bubble Nebula

The mount slews and tracks very quietly. In fact, the EQ8R-Pro is as quiet (if not quieter) than the EQ6-R Pro. Compare this to the notoriously loud Celestron CGX-L. This is certainly not a primary reason to invest in a mount, but you’d be surprised at how much this aspect matters to you when switching targets at 2am on a weeknight. 

PHD2 Guiding Graph

The judge of an astrophotography mounts tracking performance is often in the PHD2 guiding graph. I feel that it is very important to mention that the total RMS error should not be viewed as the be-all-end-all judge of the mounts tracking abilities. There are many variables that come into play here, including the settings you are using in PHD2, seeing conditions, and a lot more.

With that being said, here is a recent look at the graph I was seeing with the Sky-Watcher EQ8-R Pro during a night of imaging. This was using the On-Camera guiding setting on the Lodestar X2. I would expect pulse guiding through a direct connection between the mount and PC to be even better. 

PHD2 Guiding Graph

Practicality

The mount is extremely heavy, the EQ mount head itself (56 pounds), and especially the matching pier tripod (64 pounds). It is impossible to safely lift the tripod and equatorial mount together as a single unit. Seriously, don’t even try.

This weight makes for a rather lengthy setup routine if you are carrying the EQ8-R Pro to and from the house or garage to your yard. The tripod is not only heavy, but awkward to manage over large areas. If you have a bad back, investing in a permanent setup or buggy-style transportation device is your only option. 

Sky-Watcher EQ8-R Pro Telescope Mount

The built-in heavy-duty handles on the mount make transporting the mount head to the tripod much easier, and they actually make carrying the EQ8-R a bit easier than some of the lighter, yet more awkward mounts. In contrast, the CGX-L has a single handle, that puts your one-arm strength to the test. 

The built-in power, auxiliary, and USB 3.0 ports are extremely useful when running advanced astrophotography setups that include multiple cables running down the mount. Setups that include a cooled astronomy camera, motorized focuser, filter wheel, and guide camera will appreciate this feature the most. 

cable management

Integrated Cable Management System.

Polar Alignment

One major difference between this mount and the smaller EQ6-R is the lack of a built-in polar scope. To polar align the Sky-Watcher EQ8-R Pro you must mount the optional polar scope and l-bracket, or use an electronic polarscope as I did.

I mounted the QHY PoleMaster to the front of the telescope dovetail. This is how I polar aligned the Celestron CGX-L and 8″ RASA, so thankfully I already had the ADM PoleMaster adapter handy. 

For this method to work, you’ll want to make sure that the telescope is in the home position on both axes. On the Sky-Watcher EQ8-R Pro, it simply means using the homing sensors to find this position when you turn the mount on. After setting the home position on the hand controller, the mount will run through a series of small movements to identify true “home”. 

polar alignment

The QHY PoleMaster is a great solution for polar aligning the EQ8-R Pro. 

Adjusting the EQ8-R Pro to your latitude is done via the heavy-duty crossbar style bolt (I’d love to know the technical description for this style of bolt in the comments), which is smooth and solid. The big green knobs on either side of the mount head base allow for precise azimuth control. Everything feels extremely solid and secure, which is exactly what you would expect on a telescope mount of this caliber.

Tracking Accuracy

An astrophotography setup that includes a 32-pound apochromatic refractor telescope at 1040mm focal length demands a robust tracking platform. With two 26-pound counterweights attached to the other end, balancing this precious cargo was rather easy. More importantly, the load was secure thanks to the 3 massive locking bolts on the dovetail saddle. 

The RA and DEC axes feature a unique design I have not seen before. Each axis rotates on a massive, silver disc stating “Warning, Do Not Apply Pressure” (shown below). The Sky-Watcher EQ8-R Pro features a belt drive system in each axis to minimize backlash and reduce periodic error. The onboard computer includes a PPEC training program for those that want to maximize the precision of the mount in a permanent setting. 

RA and DEC axis

The massive silver disc design of the RA and DEC axes. 

My primary imaging camera with this setup is a Starlight Xpress SX-42 and a 7-position filter wheel. This is a monochrome CCD camera with impressive specs. An OAG (Off-axis guider) and Starlight Xpress Lodestar X2 monochrome camera handle the autoguiding for this rig, and in my first few runs with this configuration, ran exceptionally well. 

I used the popular PHD2 Guiding software to autoguide with the Esprit 150 on the EQ8-R Pro. Because the Lodestar X2 camera was fitted to the OAG on the filter wheel, I was guiding on a star using a focal length of 1040mm!

For each of the deep-sky objects I chose to photograph, I collected 5-minute exposures using 1.25 Astronomik 6nm filters. The tracking accuracy of the Sky-Watcher EQ8-R Pro was exceptional, with pin-point, round stars in each and every 5-minute exposure. Utilizing the autoguide port on the EQ8-R Pro, I see no problem shooting 10 or even 20-minute exposures with this setup.

Mount Specifications

  • Mount Type: High-capacity motorized equatorial
  • Tripod: Optional heavy-duty pier tripod
  • Power Requirements: DC11-16V, 3 amp
  • Motor Drive: 0.9° hybrid stepper motor
  • Tracking Modes: Equatorial Only
  • Alignment Procedures: 1, 2, 3 star-alignment
  • Hand controller: SynScan, PC Direct
  • Database: Messier, NGC, IC and SAO Catalogs (42,900 total)
  • Cable Management: 4 x USB 3.0, 3 x 2.1mm Power Ports, 3 X Serial Connections
  • Dovetail Compatibility: D-Style
  • Latitude Range: 10° – 65°
  • Mount Weight: 56.8 pounds
  • Tripod Weight: 64.8 pounds
  • Payload Capacity: 110 pounds

Final Thoughts

4 nights with the Sky-Watcher EQ8-R Pro is not enough mileage to write a meaningful review. I will continue to spend time with the mount over the next few months, and see how well it handles the cold Canadian winter. In the brief (clear) windows of opportunity I had, I managed to collect some impressive images using the monochrome CCD camera and filter wheel on this mount. 

Here is an image of IC 410 (The Tadpoles Nebula) captured in the Hubble palette (SII=RED, Ha=GREEN, OIII=BLUE). I captured roughly 1.5 hours worth of exposure time through each Astronomik 6nm filter and mapped the monochrome images to color channels in Adobe Photoshop. 

Tadpoles Nebula

The Tadpoles Nebula. Esprit 150 on the EQ8-R Pro Mount. 

I understand that the leap in progress (as far as image quality) is primarily due to upgrading to a monochrome CCD camera from a one-shot-color CMOS rather than the mount itself. However, this was a very demanding optical system that requires reliable tracking and operation. 

Overall, I was extremely impressed with the simple and reliable performance of the Sky-Watcher EQ8-R Pro. It made the transition from a medium-sized mount to an “observatory-class” monster a smooth transition. Personally, I have a soft spot for Sky-Watcher mounts based on my own history with the brand. 

For those looking to upgrade their iOptron, or Celestron mount to something with a greater payload capacity, you may prefer to stick to what you’re used to. Based on my early successes with this mount, and my preference to the SynScan system, I think that the Sky-Watcher EQ8-R is a top contender in this category. 

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The Rokinon 135mm F/2 was Built for Astrophotography

|Camera Lenses|21 Comments

In this post, I’ll explain why I think the Rokinon 135mm F/2 is the perfect addition to an arsenal of astrophotography lenses. 

Deep-sky astrophotography is often associated with a camera and telescope, but the truth is there are a lot of great camera lenses for astrophotography out there. In the past, I’ve covered a number of different lenses, from the Sigma 24mm F/1.4 to the Canon EF 300mm F/4L.

As you know, camera lenses come in varying focal lengths, apertures, and optical quality. Astrophotography is one of the ultimate tests of lens quality, as long exposure photography of deep-sky objects in space can highlight issues that are hidden during daytime photography.

In this post, I’ll share my results using an affordable prime telephoto lens for astrophotography, the Rokinon 135mm F/2.0 ED UMC. The version I have has the mount for Canon EOS camera bodies, but there are several different lens mounts available on Amazon.

Rokinon 135 F2 ED UMC

My Canon EOS 60Da with the Rokinon 135mm F/2.0 mounted to a Fornax Mounts LighTrack II.

This lens is available for several camera mounts, including Nikon, Sony, Pentax, Samsung, and Fuji. I purchased this lens for the purposes of wide-field deep-sky astrophotography from my light-polluted backyard (shown below), and when traveling to a dark sky site.

Taking images at this focal length from the city will swell issues with gradients, especially when shooting towards the “light dome”. For this reason, a combination of a good light pollution filter, and the use of flat calibration frames are recommended. Before I go any further, I’d like to share a photo from Gabriel Millou of the Andromeda Galaxy using a Canon 1300D.

Samyang 135mm F/2

The Andromeda Galaxy using the Rokinon 135mm F/2.0 ED UMC lens. 

To see even more example photos using the Rokinon 135mm lens (or Samyang branded version), go ahead a perform a search on Astrobin or Flickr, with the appropriate filter. I think you’ll find that this lens is behind some of the most amazing wide-field astrophotography images online!

The Rokinon 135mm F/2 ED UMC

The full name of this lens is the Rokinon 135mm F/2 ED UMC, with “ED” standing for extra-low dispersion, and UMC referring to the “ultra multi-coated” optics. This is a fully manual lens, meaning that it does not have autofocus, and you must manually select the f-stop using the aperture ring at the base of the lens.

Manually focusing a lens for astrophotography is nothing new, but the manual aperture ring adjustments may feel a little strange at first. 

Rokinon lenses are made in Korea, and so is the Samyang variation. The full extent of the relationship between Rokinon and Samyang is unknown to me, but the packaging on my lens says “Technology by Samyang Optics”. I typically shoot with Canon lenses, but the potential for low light photography (whether that’s astrophotography or the ability to film at dusk) caught my interest.

Rokinon 135mm F/2 lens specifications

The diameter of the lens is 77mm, with a non-rotating filter mount on the objective lens. The lens hood is removable (and reversible), which makes packing the Rokinon 135mm away into the included lens pouch possible. The presentation and hands-on look and feel of the 135mm F/2 lens is impressive considering the reasonable price of this lens. 

The aperture range of this lens is F/2 to F/22, with 9 diaphragm blades (aperture blades) that work in harmony to set your f-stop. The aperture ring is marked with each f-stop, and you need to manually click through F/2 – F/22 and watch the blades do their work. It’s actually kind of neat to watch!

I ordered this lens on Amazon, utilizing my Amazon Prime membership. The lens arrived next day, less than 24 hours after I hit the order button. The lens came in a handsome box, with core specifications and a lens construction diagram printed on the side. The Rokinon 135mm F/2.0 includes a lens hood, lens pouch, front and rear lens caps, and a 1-year Rokinon manufacturer warranty.

First Impressions

Overall, the lens feels very solid and well constructed. The finish and texture of the Rokinon 135mm F/2 is a step up from the 14mm F/2.8 I ordered a few years ago. 

The spec sheet for the Rokinon 135mm F/2 boasts a number of qualities, with the ones listed below being the most important when it comes to night photography and astro. Based on my handful of experiences with this lens in the backyard, I have found these traits to hold true.

  • Low-Light Performance
  • Low Chromatic Aberration
  • Low Flare and Ghosting

The image below highlights the creative freedom this lens provides. To fit the Heart and Soul Nebulae in a single frame requires an extremely wide field of view (compared to the magnification of most telescopes). The 135mm focal length is absolutely perfect for the Heart and Soul Nebulae if you’re using a crop sensor DSLR camera.

The image shown below covers 4.96 x 5.98 degrees in the constellation Cassiopeia. The images were collected using a Canon EOS Rebel T3i camera riding on a Fornax Mounts LighTrack II

heart and soul nebula

The Heart and Soul Nebulae captured using a DSLR and the Rokinon 135mm lens. 

The Rokinon website lists this lens as being useful for portraiture photography, and most telephoto applications. The shallow depth of field present at its maximum aperture does indeed create a pleasing bokeh. 

The lens hood is not petal-shaped, which is great news for those using this lens for astrophotography. The flat lens hood design allows you to easily take flat frames with the Rokinon 135mm using the white t-shirt method or using a flat panel. 

I should mention that I have only tested this full-frame lens using my astrophotography DSLR’s, all of which are crop-sensor camera bodies. This creates an effective focal length of roughly 200mm, a useful magnification for a wide variety of astro-imaging scenarios. 

I am no stranger to the full manual control of this lens, for both aperture and focus. The Rokinon 14mm F/2.8 was the first lens I had ever used like this, and these aspects do not hinder the astrophotography experience whatsoever. 

A Full Frame, Prime Lens

The Rokinon 135mm F2.0 is considered to be a full-frame lens because it can accommodate a full-frame image sensor with its 18.8-degree angle of view. In this review, however, I am using the lens on a crop sensor (APS-C) Canon EOS 60Da, which puts the field of view at 12.4 degrees.

“Prime” means that this lens is fixed at 135mm, it is not a zoom lens that allows for focal length adjustments. Prime lenses are typically lighter as they do not need the additional glass and mechanics required to zoom at varying magnifications. 

Generally, prime lenses have a reputation for being slightly sharper, and I have found that to be true whether I am shooting a nebula or a Scarlet Tanager. 

The optical design includes one extra-low dispersion (ED) lens element to control chromatic aberration, and “ultra multi-coatings” (UMC) to both improve light transmission and reduce flare. 

lens focal length

The flat lens hood is great for taking flat frames after a night of astrophotography.

Low Light Capabilities at F/2.0

The F/2.0 maximum aperture of the Rokinon 135mm lens offers a chance to collect a serious amount of signal in a single shot. This allows for less aggressive camera settings for night photography such as using a lower ISO setting and shorter exposure. 

Of course, when it comes to astrophotography, this can create some challenges as well. Focusing a “wide open” F/2 lens is demanding of the optics, especially on a field of stars in the night sky. 

One way to combat potential soft images and chasing perfect focus all night is to stop the lens down to F/2.8 or even F/4. Your images have a chance at remaining sharper once critical focus has been achieved, but now you have lost the extra light-gathering power you wanted. It’s a trade-off, and one that seems to surface time and time again in this hobby.

Although typically unused in astrophotography, I did get a chance to see the beautiful bokeh this lens creates when shooting at F/2. The aesthetic quality of the blur in the out-of-focus parts of the image are buttery smooth and soft. 

lens for astrophotography

What I Really Like

Although this lens feels solid, it is rather light when compared to a telescope. When coupled with my Canon DSLR camera, the entire system weighs just over 3 pounds. That means that it doesn’t require a robust equatorial telescope mount as a larger, heavier telephoto lens would. 

A camera tracker (or “star tracker“) is necessary for long exposure deep-sky astrophotography, but a compact model such as the iOptron SkyTracker or Sky-Watcher Star Adventurer will do just fine. 

This lens has a long focus adjustment ring, with great tension. The focuser adjustment rotates roughly 270 degrees, meaning fine-tuning on a bright star is more precise. You’ll never have to worry about losing your position just by touching the lens, but you can always tape the position down to be sure. 

The Rokinon 135mm F/2.0 ED UMC is one of the most affordable and practical lenses for astrophotography on the market. Sure, the “Nifty 50” is an incredible value (and a LOT cheaper), but the 135mm puts you within range of some of the best astrophotography targets in the night sky. 

I’ve spent a handful of nights testing this lens in my Bortle Scale Class 6/7 backyard, and my results live up to the hype it gets in terms of astrophotography performance.

Comparable Lenses (Chart)

Lens Comparison

Brand Focal Length Maximum Aperture Price
Canon 135mm F/2.0 $999 (B & H)
Nikon 135mm F/2.0 $1,391 (B & H)
Sony 135mm F/1.8 $1,898 (B & H)
Rokinon 135mm F/2.0 $499 (Amazon)

Lens Comparison

Over the years, I’ve shot deep-sky targets at varying focal lengths from 50mm to over 1000mm. The closest I’ve been to the 135mm range is 105mm on my Canon 24-105 zoom.

Not only does the Rokinon 135 add additional reach, but I can also now shoot at F/2, instead of F/4 on the Canon. Below, are a few examples of astrophotography images I’ve taken with lenses of varying focal lengths. 

As you can see, the magnification of the lens used will dictate the type of projects you shoot.

lens comparison

  1. The Great Rift of the Milky Way – Rokinon 14mm F/2.8 
  2. Mars meets Pleiades – Canon EF 24-104mm F/4L
  3. Wide-field Sadr Region – Rokinon 135mm F/2.0
  4. The Carina Nebula – William Optics RedCat 51

So what’s so great about shooting at 135mm anyway?

The RedCat is deeper at 250mm, and after that, you’re into 300-400mm territory which pulls galaxies and nebulae even closer. Why take a step back from 250 to sit between the RedCat and the 24-105?

It’s all about framing.

Image Scale at 135mm

From the moment I reviewed the first sub-exposure on the display screen of my camera, I feel in love with the mid-range magnification of a 135mm lens. My first shot was a section of the constellation Sagittarius that included the Lagoon Nebula, and Trifid Nebula.

If you want to preview the image field you can expect with a particular camera sensor and lens combination, Stellarium features a useful tool. The Image Sensor Frame tool lets you enter in the size of your camera sensor, and focal length of your lens (or telescope) to display a frame over the star map.

This is a very practical way to plan your next astrophotography project, and especially handy when using a wide field lens like the Rokinon 135mm F/2. 

astrophotography scale

You can use Stellarium to preview the image scale with the 135mm lens and your DSLR. 

At 135mm, you can get really creative about the object or objects you shoot and where you position them within the frame.

And because you can shoot between F/2 and F/4, plenty of light reaches the sensor in a relatively short exposure. This has several advantages from less demanding tracking accuracy, to being able to use a lower ISO setting.

The Downsides of this Lens

Now, I have to admit that up to this point, it sounds a little too good to be true. The downsides of this configuration are that shooting wide open can make focusing difficult.

The focuser adjustment ring on the Rokinon 135mm F/2 is excellent, but fine-tuning your critical focus on a bright star at F/2 will take some trial and error to get right. You may need to refocus your subject as the temperature changes throughout the night. 

You may need to stop down to control star bloat, and that’s exactly what I’ve done with this 135. I’ve set the f-stop to F/2.8, to sharpen up the stars a bit. In fact, in my test shots, I noticed that the red channel was a little softer than green and blue. To remedy this, I reduced the star size in post, and I started shooting at F/4 to really tighten things up.

Also, as creative as the wide-field 135mm focal length is, it’s not practical for smaller DSO’s and most galaxies. Stick to Andromeda, and skip the Whirlpool.

I have heard others mention that this lens has a “plasticky” build quality, but I believe this aspect has been improved. The model I use feels solid and the barrel is constructed with metal.

The lens is not weather-sealed, so you definitely don’t want to leave your camera and lens (and your tracking mount!) in the rain. There’s no image stabilization on the Rokinon 135mm F/2 either, but that’s a non-issue for amateur astrophotographers. 

135mm lens

The North America Nebula captured using the 135mm lens with a clip-in Ha filter.

Recommend Astrophotography Targets for this Lens

Large emission nebulae like the California Nebula (pictured below) are a great choice for this focal length. The image below was captured using a DSLR and 135mm lens on the Sky-Watcher Star Adventurer mount. 

California Nebula at 135mm

The California Nebula. Canon EOS 60Da with the Rokinon 135mm F/2 lens.

I’ve captured a lot of deep-sky astrophotography targets from the northern hemisphere, but I’m usually in too deep to capture an entire region of space at once. Here is a short list of great astrophotography targets to shoot at 135mm with this lens:

  • Orion’s Belt (Including the Horsehead Nebula, Orion Nebula, and M78
  • The Witch Head Nebula including Rigel in Orion (Careful with star reflection!)
  • The Rosette Nebula and Surrounding Nebulosity
  • Cygnus, including the North America Nebula and Pelican Nebula
  • The Sadr Region in Cygnus including the Crescent Nebula
  • The California Nebula in Perseus
  • The Blue Horsehead Nebula in Scorpius
  • The Rho Ophiuchi Cloud Complex in the constellation Ophiuchus

Below, is an incredible example of the types of projects possible with the Rokinon 135mm F/2.0 lens. The following image was captured by Eric Cauble using the Samyang branded version of this lens. 

astrophotography example image

The Sadr Region in Cygnus, including the Crescent Nebula by Eric Cauble. 

Since Eric was so generous to share his images with me, I had to include his photo of the Rho Ophiuchi cloud complex as well. This photo was captured with the Samyang 135mm F/2 lens using a UV/IR cut filter and a QHY168C dedicated astronomy camera.

Rho Ophiuchi Cloud Complex

The Rho Ophiuchi Cloud Complex by Eric Cauble using the Samyang 135mm F/2 lens. See the full-size version on Astrobin

Final Thoughts

With an effective focal length of roughly 216mm when coupled with a Canon crop sensor body, the field of view is nearly identical to the one you’d find on a full-frame camera with a 200mm telephoto lens. That’s quite a jump from 135mm, so the camera body you use with this lens may change the types of targets you shoot. 

I can’t wait to try this lens out during the winter months on some wide-field targets in Orion. The colder temperatures will make DSLR astrophotography much more practical, and there are plenty of great targets to choose from.

During the frigid months of winter, my motivation to spend over an hour setting up my complete deep-sky imaging rig dwindles. However, stepping outside to polar align a small star tracker and attach a DSLR and lens is quick and painless. 

In these situations, a portable, wide-field imaging rig wins.

Star parties or dark sky excursions are another great time to use a camera lens in place of the telescope. Not only does it let you travel light, but impressive wide field projects are often more successful when captured under a dark sky. 

For those of you that like to “pixel-peep”, have a look at the single image frame captured using the Rokinon 135mm F/2.0 ED UMC at F/4. The image is a 90-second exposure at ISO 400 using a Canon EOS 60Da. The inset picture is a magnified view of the bottom right corner of the frame. 

star test

A single, 90-second exposure using the Rokinon 135mm F/2.0 ED UMC at F/4. 

I hope that this post has provided some practical insight into a popular camera lens for astrophotography. If experience has taught me anything, it’s that the practical, pain-free equipment that gets the most use under the stars. 

This lens is available on Amazon for most camera bodies. Make sure to select your camera mount when checking the price (Check current price). If you have pictures taken using the Rokinon 135mm F/2 lens, please feel free to share your results in the comments section (links to Astrobin, Flickr or your personal gallery are fine). 

List of Compatible Cameras (Mounts)

  • Canon
  • Sony E
  • Fuji X
  • Nikon AE
  • Samsung NX
  • Pentax K
  • Sony A
  • Micro 4/3

Complete Lens Specifications (Canon)

  • Model: 135M-C
  • MSRP: $599
  • UPC: 0-84438-76410-9
  • Focal Length: 135mm
  • Maximum Aperture: F2.0
  • Coverage: Full Frame (FX)
  • Optical Construction: 11 Glass elements in 7 Groups
  • Aperture Range: F2.0 to F22
  • Diaphragm Blades: 9
  • Coating: Ultra Multi-Coating
  • Minimum Focusing Distance: 2.6ft (0.8m)
  • Filter Size: 77mm
  • Lens Hood: Removable
  • Maximum Diameter: 3.2” (82mm)
  • Weight: 29.20oz (830g)
  • Length: 4.80” (122.1mm)

lens construction

Download the User Manual

Helpful Resources:

 

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The Impressive Optolong L-eNhance Filter

In this post, I’ll share my results using the Optolong L-eNhance filter for deep sky astrophotography in the city. The L-eNhance is a dual band pass filter that ignores artificial light, yet collects a strong signal emitted by certain nebulae.

This light pollution filter was designed for color cameras, whether it’s a DSLR (a modified camera is best) or a one-shot-color dedicated astronomy camera like the one used (ASI294MC Pro) for the images in this post.

As many of you know, I mostly shoot from the city. I love to travel to dark sky locations, but imaging from home is a lot more practical, and I can do it more often. 

Optolong L-eNhance Filter

The Omega Nebula & Helix Nebula| ZWO ASI294 MC Pro + Optolong L-eNhance Filter

The problem is, the city I live in is home to over 100 thousand people, and that makes it very bright. Excessive light pollution is a reality for many of us, and I’m not sure we fully understand the long term negative effects of it yet.

The battle between light pollution and amateur astronomy wages on, but thanks to organizations like the IDA, more people are aware of the situation and making small steps in the right direction. 

Here’s a look at the light pollution I shoot through in my backyard. As you can see in this animated gif, it looks as though the light pollution increased significantly between 2018 and 2019. 

light pollution

Light pollution data from LightPollutionMap.info. 2018-2019.

For backyard astrophotographers like me, light pollution creates some serious challenges, from horrible gradient patterns to a pathetic signal-to-noise ratio. 

It seems like we have to work twice as hard as those under dark skies do to capture a beautiful image.

Fortunately, though, light pollution filters exist – and the companies that make them are getting better and better at isolating the “good” light from the bad. The argument as to whether a light pollution filter for broadband targets (such as galaxies) can actually help you collect better data continues in the forums, but I have found them to make my life a lot easier. 

However, nobody can argue the fact that a narrowband filter (often called “line filter”) can be exceptionally useful from the city. The filter I am discussing in this post is a dual-band pass filter, that collects light in two prominent emission lines, H-alpha, and Oxygen III.

transmission graph

The transmission graph of the Optolong L-eNhance dual-band pass filter.

Looking at the transmission lines of the bandpasses above, you may notice that this filter is only allowing a very selective amount of light to pass through to the camera. The good news is, some of the most incredible deep-sky nebulae in the night sky emit the majority of their signal in these two wavelengths. 

Which ones? The Eagle Nebula, Omega Nebula, and North America Nebula, to name a few. Emission nebulae are some of the most widely-photographed deep-sky targets by amateur astrophotographers, and from a filter perspective, they are much more obtainable from the city than a broadband galaxy.

Optolong L-eNhance Filter

The Optolong L-eNhance filter was designed for color cameras, such as a DSLR camera or a one-shot-color astronomy camera. The camera used for all of the example images in this post is a ZWO ASI294MC Pro, a 10.7 MP 4/3″ sensor camera with cooling. 

If you take a good look at the transmission graph, you’ll notice that the first band pass line includes both the OIII, and H-beta wavelengths. Essentially, this means that the filter should collect an even more “natural” looking image than one that isolates Ha and OIII exclusively.

The H-beta (486.1nm) emission line is nowhere near as impactful as the hydrogen-alpha line (656nm) when photographing an emission nebula target, but I like the idea of including this subtle wavelength for a more well-rounded image.

Transmission Lines

  • H-beta: 486.1nm
  • OIII: 501nm
  • H-alpha: 656nm

As you’ll see in the images shared in the post, this transmission combination leads to some surprising “natural” looking images when used with a color camera.

In the video below, you’ll see me use the Optolong L-eNhance filter for deep sky astrophotography in the backyard. Notice the bright white LED streetlamps that line my street. These artificial lights are largely ignored by the L-eNhance filter, as they do not emit light in the spectrum that passes through the filter.

In the video, I’ve threaded the Optolong L-eNhance filter (48mm version) to the field corrector of my Sky-Watcher Esprit 100 refractor telescope. The filter sits between the sensor inside my ASI294MC Pro color camera and this apochromatic refractor telescope.

Threading the filter directly to the field corrector involves carefully removing the internal ring that seals the filter glass into the housing. The reason for this is to access the threads on both sides of the filter. I do not recommend this method, as the filter glass becomes loose, and you could easily drop or damage the filter.

Instead, I would look into a filter drawer system that is compatible with your telescope. This allows you to easily swap filters in and out of the imaging train, and maintain the accurate spacing between your camera sensor and the corrector/field flattener.

L-eNhance Filter

The Optolong L-eNhance filter (48mm).

Some telescopes, such as the William Optics Zenithstar 73, or Radian Raptor 61 include a threaded slot for a 2″ filter inside of the field flattener and/or adapter. This is a very convenient location for a 48mm filter, as it is completely sealed from the elements.

Optolong L-eNhance Filter Specifications

Here are the technical specifications of this filter, coming straight from the company. I have to admit, I don’t know what most of these terms mean, but in the spirit of creating the most useful resource possible, I’ve included them for those that do. 

  • Blocking Range: 300nm – 1000nm
  • Blocking Depth: >99% light pollution line
  • TPeak: T>90%
  • Substrate: B270
  • Thickness: 1.85mm
  • Surface Quality: 60/40
  • Transmitted Wavefront RMS: λ /4
  • Parallelism (arcsec): 30s

If you don’t know what the transmitted wavefront RMS reading means in terms of the pictures you can expect to capture with your color camera, keep reading…

Imaging Results from the City

The first object I chose to photograph was the Butterfly Nebula, which is also found within the Sadr region in Cygnus. The reason I chose this target for my testing, was because this area is absolutely loaded with emission nebulae. If you have a filter that specializes in isolating H II regions, this is an area of the night sky you need to photograph.

Having used a dual band pass filter in the past (STC Optical Du0-Narrowband) from my backyard, I had a feeling that the L-eNhance would meet my expectations. I primarily shoot using a color camera, to maximize the chances of completing an image in a single night. If you are like me, a dual band pass filter may be the answer you are looking for. 

In the past, I have used a number of Optolong branded filters, including narrowband “line” filters for Ha, OIII, and SII. The Optolong L-Pro is one of my favorite broad-spectrum filters, so my experiences with this company have been stellar thus far. (They even sent me an Optolong Flag for my garage as a thank you for my video content!)

Results using a 100mm Refractor Telescope

astrophotography camera

The first image was captured using a high-end refractor telescope (ED triplet apochromat), with a focal length of 550mm. The image scale of this system is 1.7, which creates a pleasing resolution for wide-field nebulae targets like the one below. To find out the image scale of your camera and telescope, you can check out this online calculator

With a dual-band pass filter like the L-eNhance, moonlight, and the glow of my city do not interrupt a memorable imaging session in Cygnus. Below, is the image I captured using the L-eNhance filter with my ZWO ASI294MC Pro (one-shot-color) camera. The final image includes 69 x 4-minute exposures for a total integration of 4 hours and 36 minutes.

L-eNhance Filter Review

The Butterfly Nebula in Cygnus. 69 x 4-minutes.

If you would like to see all of the equipment used for this shot, I have broken everything down piece-by-piece on this page.

Below, you’ll see a breakdown of what the data looks like in each color channel, after the image has been processed and balanced as the version above. Although these images are non-linear, it should give you a better idea of how much data was collected in each color after neutralizing the background. 

The “stretched” image (the one shown above) shows exaggerated levels of data, but it does indicate the general level of sensitivity to color in each channel. 

color channels

After an extremely successful night using the L-eNhance filter on my 100mm refractor, I thought it would be interesting to see what would happen when I use it on the Celestron 8″ RASA

Results using the Celestron 8″ RASA

To use this filter with a Rowe-Ackermann Schmidt Astrograph system, it must be placed in front of the camera sensor that sits on the corrector plate of the front of the telescope. To achieve the correct spacing between my camera sensor and the optical window of the RASA, I use this Starizona filter drawer

I also installed a new Pegasus Astro FocusCube 2 motorized focuser to the RASA, for improved accuracy when focusing on this demanding F/2 optical system. The one I have was designed specifically for Celestron SCT telescopes and the RASA (This is the model I use). 

Celestron RASA

The Celestron RASA 8 F/2 with ASI294MC Pro color camera attached to the corrector plate.

As fast as the F/2 f-ratio of the RASA is, it also means that achieving critical focus manually is very difficult.  I believe that relying on camera control software to measure the accuracy of your focus precision is a must. 

Which software? Many amateur astrophotographers have had success using Sequence Generator Pro, and I personally use Astro Photography Tool. The FWHM or HFD readings of a star are needed when attempting to find (and maintain) critical focus (More on this in a later post).

Here is a better look at the FocusCube 2 installed on the RASA. The process involves removing the standard focus knob on the telescope and attaching a bracket to the base. I’ll share a new video and review of this focuser for the Celestron RASA soon. 

focuser for RASA

Pegasus Astro FocusCube 2 (motorized focuser) for the Celestron RASA.

To highlight the qualities of this filter on a telescope like the RASA, I decided to hop over to the Omega Nebula in Sagittarius. From my latitude in Canada, I have a very short window of opportunity to photograph this target. It does not reach a high apparent altitude in the sky, which makes it a demanding target for amateur astrophotographers in the Northern US or Canada.

As you’ll see in the image below, the images straight out of the camera will appear green using CMOS camera like the ASI294MC Pro. 

raw image before stretch

A raw un-stretched image (stack) using the Optolong L-eNhance filter with a color astronomy camera (ASI294MC Pro)

To create the final image, each sub-exposure was 3.5-minutes in length, with the camera set to Unity Gain. For this image, I also used autoguiding with the RASA as well (for the first time). I attached a small 50mm guide scope (Starfield 50mm guide scope) and bracket to the base of the 8″ tube. 

The ZWO ASI290mm Mini is a reliable guide camera that always pulls in more than a handful of useful stars for autoguiding purposes. 

The biggest advantage of having an autoguiding system in place with the RASA (in my opinion), is the ability to dither between frames. In previous imaging sessions with the RASA, I had no trouble capturing unguided images with round stars on the Celestron CGX-L. However, walking noise was prevalent due to a lack of the simple (yet powerful) act of dithering.

astrophotography

The Omega Nebula. Color CMOS camera with Optolong L-eNhance filter.

When it was all said and done, I ended up with 29 x 210-second exposures on the Omega Nebula through the 8″ RASA. As you can see in the processed image stack above, achieving a “near-natural” looking color balance with this dual band pass filter is possible. I can’t help but think that the additional light collected in H-beta makes a subtle, yet important difference on targets like M17. 

I also pointed my telescope towards the Helix Nebula using this filter. This planetary nebula in Aquarius is another deep sky object that does not reach a high apparent altitude in my night sky. The L-eNhance filter did a fantastic job of separating the glowing gases of NGC 7293 from a light-polluted sky. 

The Helix Nebula

The Helix Nebula. ZWO ASI294MC Pro + Optolong L-eNhance Filter.

L-eNhance vs. STC Optical Duo-Narrowband

Many readers have asked how the Optolong L-eNhance filter compares to the STC Optical Duo-Narrowband filter. In my tests, it produces VERY similar results when used an emission nebula. If you look at the transmission graphs between the two, you’ll see why.

The L-eNhance lets in a subtle amount of light in the H-beta line, which I am yet to illustrate how much of a difference this makes. The transmission peak in the OIII spectrum also appears to be wider, which may help produce a more natural looking image (at the expense of less isolated data). 

L-eNhance vs. STC Duo-Narrowband

The bottom line is, these filters act very similar, and I don’t own equipment sophisticated enough to truly show the difference between the transmission qualities of this glass. In reality, I think most folks just want a filter that compliments their color camera when shooting in the city, or under moonlight. If that is what brought you here, I think you’ll be extremely impressed with the Optolong L-eNhance.

What others are Saying…

I’m not the only one seeing great results with this filter. Ron Brecher is one of my favorite astrophotographers, and someone I look up to personally in terms of his work and his career. He uses sophisticated imaging equipment from his observatory in Canada (only 2 hours from me!) to capture stunning deep-sky objects. He shared this image on his website, and on twitter about the Optolong L-eNhance filter:

Astrodoc Review

The image was captured using a QHY 367C one-shot-color camera through a Tak FSQ-106. Be sure to visit Ron’s website to see the full-size version of the image, it’s really incredible!

Final Thoughts

Narrowband filters, especially ones that collect light in two band passes at once offer an incredible way for backyard astrophotographers to collect impactful images with a color camera. Whether you shoot with a DSLR or dedicated astronomy camera, a capable light pollution filter can be the difference between setting up twice a week, and twice a season. 

There is no substitute for dark skies, but there is hope your light-polluted backyard. The Optolong L-eNhance filter took months to develop, and as you can see first hand from my images, the results are impressive. 

If you have used the Optolong L-eNhance filter with your color astrophotography camera, please let me know what you thought in the comments. Feel free to include a link to your personal website or AstroBin profile to share an image captured with it. Seeing others work is a great way to validate the performance of this filter. 

Update, August 2020

The Optolong L-eXtreme Filter has launched, and many amateur astrophotographers agree that it is an improvement over the L-eNhance. This version of the filter isolates the OIII bandpass at 7nm, without including H-Beta, and the small bandpass between OIII and Hb.

The resulting images appear to be more dynamic with better contrast. The following image of the Veil Nebula was captured using the Optolong L-eXtreme filter and a QHY268C one-shot-color camera.

Veil Nebula

The Veil Nebula. Captured using the Optolong L-eXtreme Filter.

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Sky-Watcher EQ6-R Pro Review

|Equipment|35 Comments

The Sky-Watcher EQ6-R Pro is a computerized equatorial telescope mount with GoTo capabilities. This equatorial (EQ) mount is capable of providing precise, accurate tracking of the night sky, and is suitable for long-exposure astrophotography. 

The core specifications of this equatorial mount include having a built-in ST-4 autoguider port, a payload capacity of 44 pounds, and a SynScan computer hand controller with an extensive database of objects. 

I have been using the Sky-Watcher EQ6-R Pro telescope mount since October 2018, and have used it to capture several deep sky images of nebulae, galaxies, and star clusters in space. In this post, I’ll share some of my favorite features of this EQ mount that I have experienced over several imaging sessions in the backyard.

Sky-Watcher EQ6-R Pro Review

The Veil Nebula captured using the EQ6-R Pro telescope setup shown on the right.

Whether you already own the EQ6-R Pro and are looking to tap into more of its features, or are trying to decide which equatorial mount is best for your visual observation or astrophotography goals, this article should offer up some useful input from someone who’s been in your shoes. 

Related Video: My first run with the Sky-Watcher EQ6-R Pro in the backyard

Sky-Watcher EQ6-R Pro telescope mount

Sky-Watcher EQ6-R Pro Review

Before we dive into some of the interesting features you may not have known about, here is an overview of exactly what the “EQ6” is capable of. As a preface, it’s worth noting that I use this mount for astrophotography exclusively, and I am in the northern hemisphere.

For those in the southern hemisphere, the process is very similar all around, aside from polar aligning the mount with the south celestial pole (SCP).

Before stepping up to the EQ6-R, I used a number of intermediate level astrophotography mounts, including the slightly smaller HEQ5 Pro SynScan model. 

Sky-Watcher EQ6-R Pro

The Basics

The EQ6-R Pro includes a SynScan hand controller with an LCD display that gives you control it’s features and basic functions. The left and right keys on the keypad control the Right Ascension (RA) axis, while the up and down arrows are used to control the Declination (DEC) axis. 

You can control the slew speed by selecting the RATE shortcut button (2) on the keypad, as it is useful to make large movements at a high speed, and subtle adjustments using a slow speed. The Sky-Watcher EQ6-R Pro has 10 slew speeds for complete control over the movement of each axis. 

Before powering up the EQ6-R, your telescope should be in the home position. This means that the EQ head is leveled on the tripod, and the RA axis is pointed towards the north celestial pole (NCP). The counterweight should be at its lowest position, and the telescope should be pointing towards the NCP.  You can then turn on the mount and select the operation mode. 

For those interested in astrophotography, you will only ever want to use the mount in EQ mode. 

Iris Nebula

The Iris Nebula in Cepheus captured using the setup shown on this page.

With the RA and DEC clutches locked, and counterweight(s) attached, you can mount your telescope on top of the EQ head. This is accomplished by fastening the mounting plate of your telescope to the saddle, which accepts both D and V-style mounting plates.

If you are looking for a nice upgrade, the Dual EQ6R-Pro XL collar was redesigned to fit the EQ6R-Pro and features two large locking hand knobs and spring-loaded jaws.

EQ6-R adm saddle upgrade

Dual EQ6R-Pro XL collar

Getting Started

Once the SynScan system has initialized, you can enter in the geographic coordinates of your observing site.

This involves entering the latitude and longitude coordinates of your current location using the cursor on the LCD display and the keypad. Then, you will enter your current time zone, which for me, happens to be UTC -4 in southern Ontario. 

You can also enter in your current elevation, which is used for atmospheric refraction compensation (generally, the higher your elevation, the better). Next is setting the current date and time, and whether you are currently on daylight savings time.  

Once all of these important details have been entered (so the mount understands what is available in the sky from your location), you reach the mount alignment process, with the “Begin Alignment” dialog served up on the LCD screen. 

SynScan Hand Controller

The SynScan Hand Controller set to EQ Mode. 

Use the “Park” Feature

This simple, yet useful feature automatically aligns your telescope mount in both axes at the beginning of your imaging session. It is not exclusive to the EQ6-R Pro, yet it is easy to miss if you don’t follow the instructions in the manual on your first few runs. 

This feature is located under the “Utility Function” menu and asks you to turn off the mount after the park position has been confirmed. The next time you turn the mount on, you will see a dialog on the LCD display asking if you would like to start from the park position.

This is a handy feature that I did not personally take advantage of for the first few months of ownership with the mount. It is nice to confirm the home position when setting up, especially before beginning your polar alignment process.

The EQ6-R is Easy to Polar Align

Whether you use the built-in polar scope with the illuminated reticle or use a QHY PoleMaster device, polar aligning the EQ6-R is a breeze. 

This largely due to the fact that the EQ6-6 includes large, Alt/Az adjustment bolts with comfortable handles. Fine-tuning the polar axis of this equatorial telescope mount is possible thanks to these convenient controls.

The built-in polar finder scope with an illuminated reticle allows you to accurately polar align the mount without the need for additional software or accessories. You can either use a third-party mobile app like “Polar Finder” to find out the current position of Polaris, or simply use the information displayed on the SynScan hand controller. 

The SynScan hand controller displays the position of Polaris in polar scopes field of view (FOV). You need to imagine that the large circle in the FOV of the polar scope as a clock’s face with 12:00 sitting at the top.

Then, it’s simply a matter of adjusting the Alt/Az bolts of the mount to place Polaris in the “HH:MM” position provided.

Using a PoleMaster with the EQ6-R

If you don’t like getting underneath the polar scope for a real-time view of the NCP or SCP, the QHY PoleMaster is a great option. This electronic polar scope uses a small camera to display the region surrounding the north (or south) celestial pole. 

Using the live feed through the camera, you can fine-tune your Alt/Az adjustments in a very precise manner. The PoleMaster requires the appropriate adapter (this is the one you need) to fasten it to the polar axis.

QHY PoleMaster Adapter

Fastening the PoleMaster to the EQ6-R using the necessary adapter.

You Can Improve the Alignment Accuracy

Before running a star alignment routine, make sure that your telescope is well balanced, and that there are no loose cables that could get caught and snag on the mount. 

The alignment routine involves choosing a bright, named star from the database and centering it in your telescope eyepiece or camera. The LCD screen displays “Choose 1st Star”, at which point you can cycle through the list to find a star that is not blocked by any obstructions from your location and press enter.

A word of caution here, once you hit enter, the mount will start to slew to the object immediately. 

From here, it’s a matter of using the arrow buttons on the keypad to center the star. Remember, you can change the slew speed at any time by pushing the “Rate” button and setting the value higher or lower. It is often useful to leverage a finder scope on your telescope when slewing to your first alignment star, as it has a much wider field of view than your primary telescope and makes finding the first star easier. 

When running through a star alignment routine, it is important to consistently center the alignment star in the eyepiece or camera’s FOV. It is beneficial to use a reticle eyepiece with a small FOV. Personally, I use the camera’s FOV and center the star on my DSLR display screen (with grid-enabled), or with a cross-hair overlay in my camera control software (Astro Photography Tool).

You can run a 1,2, or 3-star alignment to improve the pointing accuracy of the telescope. This is very important when it comes to photographing deep-sky objects that are nearly invisible until a long exposure image is collected. 

Tulip Nebula

The Tulip Nebula in Cygnus using the EQ6-R Pro mount for tracking.

Avoid Errors due to Mechanical Backlash

You can improve your alignment accuracy by avoiding errors due to mechanical backlash. Backlash is present in all equatorial telescope mounts and does not affect your observing enjoyment, or your long exposure images when autoguiding is employed.

To avoid introducing alignment error caused by backlash, center the alignment star ending with UP and RIGHT directions from the keypad. If you overshoot the star using this method, use LEFT and DOWN to bring the star back down the FOV and try again.

Computerized Telescope Mount

The Stepper Motors are Quiet

If you haven’t used this particular mount first hand, you may be wondering what the EQ6-R sounds like while it is slewing. I have heard many astrophotography mounts over the years, and this one is impressively quiet. 

This mount uses stepper motors with a 1.8° step angle and 64 micro steps driven. This technical design aspect results in a quieter mount than on using servo motors.

This means that even at the maximum slew speed (9X), the mount emits a modest hum that will not wake up your neighbors. While the telescope mount is tracking, it is completely silent. It’s only when you move the RA or DEC axis at top speed that you hear a noise.

Compared to other equatorial telescope mounts I have used, the audible sound the EQ6-R Pro makes is more than acceptable. When you are partaking in a hobby that takes place (alone) outside at night, avoiding loud or unusual noises when possible is always a good idea.

In contrast, the Celestron CGX-L computerized mount is noticeably loud while slewing at top speed. If this mount is being used in a closed observatory, it’s not an issue. However, I set up my equipment in a city neighborhood backyard. Depending on the time of night, I hesitate slewing to a new target because of this trait. 

The Autoguiding Performance is Impressive

The Sky-Watcher EQ6-R Pro delivers impressive results when the built-in autoguider port is leveraged. Over the years I have maximized the tracking capabilities of my astrophotography mounts by using an auxiliary guide scope and camera to autoguide using free software called PHD2 guiding

The EQ6-R Pro allows you to set change the default auto guide speed of the mount of 0.5X to 0.75X or 1.0X in the setup menu.  

I have experimented using a guiding rate of 1.0X and saw little improvement to my guiding graph in PHD2 guiding over the default speed of 0.5X. The point is, you have the option of adjusting this setting if the need calls for it, and it’s a feature I’ve only recently tapped into on the EQ6-R Pro.

For a real-life example of the autoguiding performance, you can expect with this mount, have a look at the screenshot below. The guiding graph shows that my total RMS error is 0.63″. Generally, a total RMS error of under 1-second means that you can expect pinpoint stars in your long exposure images.

EQ6-R autoguiding graph

My autoguiding graph in PHD2 guiding using the Sky-Watcher EQ6-R Pro SynScan mount. 

The Mount is Heavier Than it Looks

When it comes to equatorial mounts for astrophotography, being heavy is a good thing. However, I think some people that receive their EQ6-R for the first time may be a little surprised at how heavy the EQ6-R actually is (I was).

The weight of the EQ head is 38 lbs on its own, and the tripod adds another 16.5 lbs. Add in two 11-lb counterweights, and you’ve got a telescope rig that weighs 76.6 pounds and is not going anywhere for a while.

Luckily, the EQ head includes a useful carry handle that I have certainly put to good use. Also, the supplied counterweight bar is retractable, which makes transporting the mount out the door of my garage a little easier. 

mount specifications

I used to carry my Sky-Watcher HEQ5 Pro SynScan around the yard with the telescope and counterweight attached. It was heavy and awkward, but manageable.

This is not possible with the EQ6-R, which is understandable considering the increased payload capacity (44-lbs) of the mount. To transport the Sky-Watcher EQ6-R from my detached garage to the yard, I must remove the counterweights and the telescope first.

It’s possible to lift the tripod with the EQ head attached (54.5 lbs), but this is likely too heavy for most folks. The good news is, this heavy profile means that accidentally bumping the polar alignment out of position by kicking a tripod leg is unlikely. Smaller, ultra-portable mounts like the iOptron SkyGuider Pro do not share this quality. 

You Don’t Need to “Mod” the Mount

If you’re a tinkerer, I get it. It may be tempting to you to open up the EQ mount head and take a look. I would advise against this personally, as you may do more harm than good.

I’ve seen a number of posts and videos discussing “belt-mods” and “hyper-tuning” Sky-Watcher NEQ6 and EQ6-R mounts. Personally, I wouldn’t recommend opening up the mount in hopes of tweaking performance, even if the underlying mechanics are straightforward to you.

In my experience, the Sky-Watcher EQ6-R can track accurately for 10-minute exposures (or longer) without any re-greasing or modifications to the worm gears when autoguiding is leveraged.

I suggest spending the time to get your balance and polar alignment spot-on before blaming the mount for bad tracking. It’s easy to get caught up in scrutinizing the mechanical backlash and periodic error present in the mount.

If you do dive into these advanced adjustments, you better be mechanically minded and ready to invest a “minimum of four hours” for a typical belt modification. 

astrophotography telescope

The EQ6-R with a Sky-Watcher Esprit 100 ED APO attached.

The SynScan Hand Controller gives you Extensive Options

The included SynScan hand controller includes an impressive 42,000+ object database, with almost every possible target you could ever want to observe or photograph.

The Messier object list gets a lot of use for amateur astronomers in the Northern Hemisphere, while the NGC catalog is great for pointing the telescope at more obscure nebulae and star clusters.

The database also includes IC and Caldwell catalogs, which covers most of the noteworthy subjects in the night sky. I only wish the database included the Sharpless catalog, for items such as the Tulip Nebula with no alternative designation.

To slew to these objects, it may be better to control the EQ6-R using your PC using a supplementary PC-Link cable along with the appropriate ASCOM drivers and software.

I use the hand controller to align and center my target. After a quick polar alignment routine using the QHY PoleMaster, the pointing accuracy of the mount is spot-on using just a 1-star alignment.

After you’re aligned and ready to observe or image an object in space, you can start by choosing a target using the “OBJECT” shortcut key, which contains the following object list:

  • Named Stars
  • Solar System
  • NGC Catalog
  • IC Catalog
  • Messier Catalog
  • Caldwell Catalog
  • SAO Catalog
  • Double Stars
  • Variable Stars
  • User Object
  • Deep Sky Tour

The deep sky tour is a very cool feature for visual observation sessions. Imagine a star party or public outreach event where you want to have the best list of targets at the ready.

This feature generates a list of the most famous deep-sky objects that appear in the current night sky overhead. You simply go through the list and pick them off one by one.

The Periodic Error Correction (PEC) Feature

Periodic tracking error is present in all equatorial telescope mounts, and is due to the design of the internal gears. The Sky-Watcher EQ6-R includes a periodic error correction (PEC) function to help correct this.

The PEC training procedure requires that you first polar align and star align the telescope mount. Then, slew to a star close to the celestial equator, and center it in the telescope eyepiece or imaging camera.

Then, navigate to the Utility Function > PEC Training mode and press enter. From here you can select the speed you would like to use for PEC training. The Sky-Watcher SynScan manual suggests using 0.125X sidereal rate for wider FOV telescopes such as the Esprit 100 ED APO.

After selecting the speed using the “1” or “2” keys, the screen will then start to display the elapsed time of the PEC training routine. Now, your job is to keep the star centered in the FOV using the left and right direction keys on the hand controller.

Once the PEC training routine has completed, the elapsed time will stop. Noe, you can select “PEC+Sidereal” as a tracking speed in the Setup menu. It is recommended to wait for at least one PEC training reply cycle to complete before you start taking your images.

Sky-Watcher SynScan Specifications

  • Object Catalog: Messier Catalog, NGC, SAO, Caldwell, Double Star, Variable Star, Named Star, Planets
  • Pointing Accuracy: Up to 5 arc-minutes RMS
  • Tracking Rate: Sidereal Rate, Solar Rate, Lunar Rate
  • PEC: PPEC (permanent PEC)
  • Database: 42,000+ Objects
  • LCD: 18 Characters X 2 Lines (adjustable contrast and backlight)
  • Keypad: Rubber with adjustable backlight
  • GPS: SynScan GPS Modular (Optional)
  • PC Connection: USB or RS-232X
  • Power Output: Power Supply Voltage – 0.7V, Max. 100mA current output

Power Supply for the Sky-Watcher EQ6-R Pro

As one Cloudy Nights forum member put it, the Sky-Watcher EQ6-R Pro can get “cranky” if the right power supply is not used. I have experienced this issue myself, when I used an AC to DC power adapter that did not provide a minimum 4 amps of power.

These days, I use a 12V AC/DC adapter with 6 amps to power the EQ6-R when plugged in at home. Here is a picture of the exact AC/DC adapter I use with the EQ6-R, and here is a link to it on Amazon. Others have found the Pyramid PS9KX 5 Amp power supply to work well with this mount. 

Power supply for EQ6-R Pro

The AC/DC adapter I use to power the EQ6-R Pro mount from home. 

Final Thoughts

As you may have noticed, there is a lot to cover when discussing all of the features of the Sky-Watcher EQ6-R Pro SynScan computerized telescope mount. The very first night I used the EQ6-R, I captured one of my favorite astrophotography images to date, and I knew I was in a for a long relationship with this mount. 

A reliable equatorial mount is the foundation of every great deep sky astrophotography kit, and the EQ6-R is a worthy investment for those looking for a stable, long-term solution for long-exposure imaging.

From my early days with the HEQ5 Pro to my latest session in the backyard with the EQ6, I’ve been extremely satisfied with the user experience and performance of Sky-Watcher’s affordable equatorial telescope mounts. 

astrophotography telescope mount

Pros:

  • Fantastic Tracking when Autoguiding Used
  • Quiet Stepper Motors even Slewing at 9X
  • Easy to Polar Align
  • Built-In PEC Training Feature

Cons:

  • Heavier Than it Looks
  • Intermediate Level Mount with Price to Match
  • Power Supply must be Correct or will Act Up

What Others Have Said:

“This mount is simply amazing. It is robust and tracks very well. I was taking 5-minute subs with no star trails. It is built like a tank and handles my Meade 5″ refractor with ease. The stepper motors are quiet. It’s simply a joy to use and I highly recommend it. The price is well worth it” – James S. on HPS website

“This mount is a tank. I have been doing astrophotography for several years using a lighter weight mount but I was ready to setup up to a heavier payload mount and I am very pleased.” – Ray on HPS website

twitter review

The Sky-Watcher EQ6-R Pro is Available at OPT

EQ6-R Pro Review

Useful Resources:

Do you use the Sky-Watcher EQ6-R Pro for astrophotography? If so, let me know your experiences with it in the comments. To stay up to date with my latest adventures in the backyard, be sure to subscribe to my newsletter. Until next time, clear skies!

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QHY PoleMaster Review

|Tutorials|26 Comments

The QHY PoleMaster electronic polar scope was designed to make your polar alignment routine easier, and more precise. No matter which camera tracker or equatorial telescope mount you’re using, when it comes to astrophotography, accurate polar alignment is critical.

If you have ever struggled to polar align your telescope mount with the north or south celestial pole, the QHY PoleMaster may just be your new best friend. With a slew of recent technical headaches and an unforgiving winter, my appreciation for devices that make my life easier has grown.

The QHY PoleMaster delivered exceptional results for me on my first night out with it. The dedicated polar alignment software was easy to use, and the camera produced a crystal clear image of the starfield surrounding the north celestial pole.

I experienced that cliche moment I expect all backyard astrophotographers had with this device their first night where I thought, “I should have been using one of these a long time ago”. It’s true.

QHY Polemaster

 

The PoleMaster I am using is for my Sky-Watcher EQ6-R Pro EQ mount, and I have fastened it to the mount using the dedicated QHY adapter for this model.

QHY PoleMaster Review

In this post, I’ll review the QHY PoleMaster from the perspective of an experienced amateur backyard astrophotographer who’s spent a lot of time manually polar aligning mounts using polar finder scope.

When others would mention the QHY PoleMaster to me, I would say that I just don’t need one. I felt comfortable manually polar aligning my telescope mounts and camera trackers, from the iOptron SkyGuider Pro, to the Sky-Watcher EQ6-R Pro.

deep sky astrophotography equipment

My deep-sky astrophotography setup with a PoleMaster fastened to the polar axis of the telescope mount.

I use a mobile app (Polar Finder) that gives me a readout of the current position of the north celestial pole, and fine-tune the altitude and azimuth controls of my mount to line the axis up as best as possible. On the Celestron CGX-L, I have the All-Star Polar Alignment feature to help me out.

So why do I need a QHY PoleMaster to aid me in this process? Because sometimes “as best as possible” just isn’t good enough. Oh, and kneeling on the cold pavement or wet grass to get behind that polar scope kinda sucks too.

What about confirming the position of Polaris in the illuminated reticle after I’ve started imaging? Depending on the angle my telescope is pointed (on the EQ6-R), this simply isn’t an option. In fact, there is a long list of benefits to using the QHY PoleMaster over a manual alignment routine that I seemed to have ignored up until now.

Polar Alignment speed, accuracy and experience improvements with the QHY PoleMaster:

  • I can polar align faster, at dusk

My old method of polar alignment was fast, this one is faster. I no longer need to wait until I can see Polaris with my naked eye to get started.

  • I don’t have to get on the ground

I like to leave my telescope mount tripod legs at their minimum height for maximum stability. However, this makes getting underneath the polar scope tricky and somewhat painful (I feel old).

  • Improved polar alignment accuracy

A high precision camera can achieve a higher level of polar alignment accuracy than “my best try”. The imaging camera in the PoleMaster has a resolution of 30 arc seconds.

  • I can monitor and confirm my polar alignment at any time

Any slight amount of drift due to bumping the mount, sinking into the lawn or other factors I had no way of monitoring are now easy to identify and fix.

  • No more 3-star alignment routines

electronic polar scope

Why didn’t someone tell me about this feature? The spot-on accuracy of the PoleMaster means that only a 1-star alignment routine is needed for your telescope mount to learn the sky.

The pointing accuracy of your telescope mount will vary depending on the focal length of the telescope you are using for astrophotography.

Eliminating any cone error in your telescope mount will improve your pointing accuracy even further. The Sky-Watcher EQ6-R Pro has an option to adjust this.

QHY PoleMaster EQ Mount Polar Alignment Camera Specifications:

  • Field of View: 11 degrees by 8 degrees
  • Interface: Mini USB 2.0
  • Resolution: Approximately 30 Arc seconds
  • Weight: 115 g (0.25 lb)

What’s included in the box

This PoleMaster was sent to me from High Point Scientific for review. The team at High Point made sure to include the necessary adapter for my EQ telescope mount. Here is a look at everything that comes with the PoleMaster:

  • PoleMaster camera body
  • Lens cap with a lanyard
  • Mini USB 2.0 cable
  • Mount adaptor
  • Mount adaptor cap
  • M4 hardware for attaching the adaptor
  • Allen key for lens focus adjustment

what's included

When ordering your PoleMaster, make sure to specify which mount adapter you need for your specific telescope mount.

View list of available mount adapters

Fastening the PoleMaster to your telescope mount

The PoleMaster I am using is for my Sky-Watcher EQ6-R Pro EQ mount, and I have fastened it to the mount using the dedicated QHY adapter for this model. The hardware was easy to install, and the materials used and overall finish of this device is attractive.

The adapter for my Sky-Watcher EQ6-R came with a tiny Allen key to adjust tension, so I could securely lock the PoleMaster into the front of the polar axis scope of the mount. The adapter I am using for the Sky-Watcher EQ6-R also works with CGEM style mounts from Celestron.

PoleMaster adapter for Sky-Watcher EQ6-R Pro

The QHY PoleMaster Adapter for the Sky-Watcher EQ6-R

There are two parts to the mount adapter for the PoleMaster, the camera base disc that attaches to the camera body, and the camera mount ring that you need to secure to the mount. You secure the camera base disc to the mounting ring using a thumbscrew.

For the EQ6-R mount adapter I used, there were three tiny grub screws to tighten using the supplied Allen key to lock the adapter into place. 

I have also mounted the PoleMaster to a Celestron CGX-L telescope mount using a Celestron ADM adapter. The adapter clamps to the dovetail bar of the imaging telescope (In the example below, an 8-inch RASA). This adapter worked exceptionally well when polar aligning the Celestron CGX-L for imaging without the use of autoguiding.

Celestron Adapter

The PoleMaster mounted to a Celestron CGX-L mount and RASA telescope using an adapter.

The device connects to my PC via a Mini USB 2.0 cable, with miniature locking screws to avoid yanking the cable out by accident. I wish more of my device connectors had this. The manual instructs you to position the USB port of the PoleMaster to the left-hand side when looking at the device head-on.

I ran the mini USB 2.0 cable from the PoleMaster into my recently upgraded powered USB hub, which consolidates the various astrophotography devices I have running to a single USB cable into my laptop.

The adapter allows you to take the PoleMaster off of the mount while not in use or in storage, but I think I’ll leave it right where it is. The tiny camera adds no weight to my rig and maintains a low profile.

I’ll just have to make sure I don’t bang anything against the device by accident when setting up. The included lens cap should stay on the PoleMaster when not in use to protect the lens.

QHY PoleMaster Adapter

There are several adapters available for the PoleMaster to fit with your specific telescope or camera mount. From small camera trackers such as the Sky-Watcher Star Adventurer to monster mounts like the Celestron CGX-L. Be sure to speak with the vendor about which adapter you need for your mount.

For mounts like the Celestron CGX-L that do not have a polar axis scope in the mount, a specialized L-bracket and adapter is needed to mount the device. In the photo below, you’ll see how I have mounted the PoleMaster underneath the dovetail rail of the 8″ RASA F/2.

Celestron QHY PoleMaster adapter

The PoleMaster mounted to the CGE dovetail rail of the Celestron RASA.

Looking for a dedicated electronic polarscope for the iOptron SkyGuider Pro? If you haven’t found an adapter to mount the PoleMaster to this mount, consider the iOptron iPolar device. The iPolar and adapter were made specifically for the iOptron SkyGuider Pro. 

Software and Downloads

All of the software and drivers needed to run the PoleMaster device were found on the QHY website. The company has recently updated its site, which lead me on a bit of a wild goose chase.

Rather than using the URL printed on the green card that came with the camera, I simply “Googled “QHY PoleMaster Driver” to find the appropriate section of the QHY website.

Here, I downloaded the latest stable driver for the PoleMaster, along with the dedicated software needed to communicate with the camera and control parameters such as gain and exposure length.

With the 2 downloads unpacked and installed, I ran the PoleMaster software on my field laptop with the camera connected. The QHY PoleMaster manual (link below) was to-the-point and helpful through this process and instructed me to click the “connect” button.

QHY PoleMaster Manual

QHYCCD PoleMaster Manual

I heard the reassuring “new device connected” chime on my Windows 10 OS after plugging in the PoleMaster, so I new the camera was successfully recognized by my PC.

Tip:

If your PC has trouble recognizing astrophotography accessories and devices, I recommend unplugging the device and reconnecting to a new USB port. Monitor the Windows device manager to troubleshoot any connection issues.

After hitting the “connect” button, the PoleMaster delivered a live-view loop of the stars in the northern sky. The mount was already roughly polar aligned to my latitude at 43 degrees north and pointed in the general direction of Polaris in my backyard.

The PoleMaster camera lens has an 11 x 6 degree of field of view. This means that the pole star should be visible if the mount has been roughly polar aligned.

Even though it was not completely dark out yet, I could see a formation of stars in the display screen right off the bat. After zooming out to 75% view, the north star, Polaris was obvious.

Us northern hemisphere folk have the luxury of having a bright pole star. In the southern hemisphere, the PoleMaster Uses Sigma Octans as a reference, which is a bit trickier to identify.

Using the PoleMaster Software

PoleMaster software

The PoleMaster software user interface.

The first thing you’ll want to do is adjust the gain and exposure settings so that it is easy to identify the pole star and a number of adjacent stars in the field.

The software walks you through a simple process of identifying and confirming the pole star. The process involves matching an overlay of star positions with your current view of Polaris and surrounding stars.

The rotate tool on the left hand sidebar lets you rotate the star pattern overlay using your mouse or trackpad to line up with your current live view of the north star.

Then, you are asked to rotate the RA axis of your telescope mount to determine the rotation of the mechanical axis. By rotating your mounts right ascension axis by 15 degrees or more, the software can confirm this value.

AstroBackyard Polemaster Review

Fine-tuning the polar alignment accuracy of my telescope mount using the QHY PoleMaster.

I made the mistake of releasing the RA clutch of the mount to perform this step when the manual clearly states that this must be done using the hand controller or mount control software such as EQMOD.

The reason for this specification is that by releasing the RA clutch, you shift the rotational center of the mount. Instead, keep the RA clutch locked, and perform this rotation by pressing the east button on the keypad.

Next the on-screen prompts tell you to confirm the center of rotation. Eventually, you will get to a point where the application displays a small green circle. This is exactly where the pole star needs to be. At this point, the ultra-fine adjustments you make to your polar alignment are far beyond what’s possible with the naked eye.

I wonder how far off the north celestial pole I was in the past?

North celestial pole

Aligning the polar axis of my telescope mount with the true north celestial pole using the PoleMaster.

Atmospheric Refraction

The PoleMaster has an option to enable a feature called atmospheric refraction to further improve your polar alignment accuracy. This feature asks you to input your coordinates, temperature, and pressure. For atmospheric refraction to work correctly, the USB connector on the PoleMaster must be facing east. 

Owners of the PoleMaster have recommended to start the polar alignment routine with your telescope to the west instead of the home position. 2 moves or more than 30 degrees can be difficult from the home position, so if the telescope starts in the west it is not an issue.

If you do not remove the PoleMaster from your telescope mount between astrophotography sessions, you can reuse the centering procedure from your previous polar alignment. However, if you are using the atmospheric refraction feature, you’ll need to remember to adjust the temperature and pressure settings for that night.

PHD2 Drift Alignment for Improved Accuracy

Some amateur astrophotographers has found that by using the drift alignment tool in PHD2 guiding, you can improve your polar alignment accuracy even further with the PoleMaster. The drift align tool in PHD2 works by measuring the error (drift) of a star and adjusting the mount to reduce the error.

You repeat the process of measuring the drift error and adjusting the mount by adjusting the altitude and azimuth bolts until the drift error is as close to zero as possible. Because this feature of PHD2 gives you a way to measure the amount of drift error in your polar alignment, it can be a useful way to really dial in the accuracy of your polar alignment that you have determined using the PoleMaster.

I have never went to these lengths to confirm the preciseness of my polar alignment myself, but if you are interested, you can watch this presentation on the Astro Imaging Channel. For those that are setting up a permanent observatory, I can see how this level of accuracy justifies the commitment of time.

The Pinwheel Galaxy

My photo of the Pinwheel Galaxy using the QHYCCD PoleMaster for polar alignment on the Celestron CGX-L mount.

Final Thoughts

There is a reason so many amateur astrophotography enthusiasts own a QHY PoleMaster. Whether you want to improve your polar alignment accuracy, save time, or ditch those 2nd and 3rd alignment stars when setting up – the PoleMaster can make your time under the stars more efficient.

The pressure and urgency to capture images increases when you have a limited window of clear sky time. When even a single aspect of your astrophotography setup is off, you can quickly squander your night sky bounty for the night.

astrophotography telescope

Devices like the QHY PoleMaster help to optimize your imaging experience and allow you to focus on the photography side of things, like collecting images. The peace of mind knowing that your telescope mount is optimized for the apparent rotation of the night sky is one aspect of the hobby every one of us can appreciate.

At under $300 USD for the QHY PoleMaster Electronic Polar Scope is an obvious upgrade to any amateur setup, whether you think you need one or not. Is it possible to get your rig accurately polar aligned without the PoleMaster? Sure.

But in a hobby where little things make the difference between a good image, and a great one – I like to take every advantage I can get.

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ZWO ASI294MC Pro Review

|Camera|45 Comments

The ZWO ASI294 MC Pro is a remarkably capable one-shot-color CMOS camera for deep sky astrophotography. Whether you use it for broadband true-color images on a moonless night or ultra-long-exposure images using your favorite narrowband filter – this camera can produce insanely beautiful images.

This is easily one of the best color cameras I have ever used for astrophotography and my go-to choice for a night of deep-sky imaging. Over the past year, I have used this camera extensively through a number of telescopes in the backyard and beyond.

Here is a taste of what the ASI294MC Pro can do:

M20 - The Trifid Nebula

The Trifid Nebula using a Luminance Filter with the ASI294 MC Pro

This photo of the Trifid Nebula was captured using the ZWO ASI294MC Pro with a Luminance filter (IR Cut) in front of the sensor. The photo was captured under the dark skies of the Cherry Springs Star Party in 2018.

The ASI294MC Pro has proven to be an incredible 4/3 sensor CMOS astronomy camera in the astrophotography community. This camera is responsible for my best deep-sky images to date, including the photos shown below.

ZWO ASI294MC Pro Images

It is the best camera I have ever personally used for astrophotography, and I continue to use it to this day. At under $1K (US), you’ll be hard-pressed to find a more versatile, reliable, and easy-to-use color astronomy camera.

This camera works exceptionally well with broadband light pollution filters and narrowband filters. Many people will advise you not to use a color camera with narrow bandpass filters such as H-alpha or OIII, but I have found the 294MC Pro to perform extremely when used with a duo-narrowband filter.
where to buy

Order the ZWO ASI294MC Pro Camera

If you want to see what others are doing with the ASI294MC Pro, have a look at the #ASI294MCPro hashtag on Instagram, and you’ll see that it’s not just me. You can also see exquisite example images with this camera on Astrobin. 

ZWO ASI294MC Pro Astrophotography Camera Review

I can safely say that I now know exactly what the ASI294MC Pro is capable of, and some recommended settings that you can use for a successful image. I’ve used this camera for both full-color images with light pollution filters, an IR cut filter and narrowband filters that separate certain wavelengths of light such as Ha and OIII.

This OSC (One-shot-color) camera performs exceptionally well in both situations. The idea of capturing narrowband images with a color camera is something that is generally advised against in the astrophotography community. This is because a color sensor will essentially record about one-quarter of the detail a mono camera would.

The cheat code, however, is to use a color camera like the ASI294 MC Pro with a duo-narrowband filter like the STC Astro Duo-Narrowband filter. This has the power to build gorgeous deep sky images like the Eagle Nebula example below in a single shot.

eagle nebula

The Eagle Nebula in Ha + OIII (STC Astro Duo-Narrowband Filter)

The photo above was captured in a Bortle Scale Class 8 light-polluted area (my backyard) using the ASI294 MC Pro. It showcases both Ha and OIII gases of this Emission Nebula (Messier 16) for some astonishingly detailed results from the city.

This dedicated astronomy camera houses a high-sensitivity type 4/3 CMOS image sensor that supports 4K output at 120 frames per second. It’s a SONY 10.7 MP sensor that produces high-resolution 4144 x 2822 pixel images at its native resolution.

I generally bin my images 2×2, so that just means that my photos are half of that size, in greater resolution. (smaller pixel size). The Bayer pattern of this color sensor is RGGB, which you’ll need to remember when selecting the camera in your image control software, and before stacking.

This camera is well suited for color EAA astronomy (Electronically-Assisted Astronomy), as the ASI294MC Pro includes a 256MB DDR3 memory buffer to help improve data transfer reliability. This is a great feature to consider if you plan on diving into this type of visual astronomy.

You can benefit from the high sensitivity sensor to view more detail in a deep sky object in a “live” looping video feed. Because I am obsessed with collecting images, the only time I experience a glimpse of this feature is when I am framing my target!

Comparing Specs Between ASI Color Cameras:

Camera Sensor Sensor Size Resolution Price
ASI183MC Pro SONY IMX183 1" 20 MP Check Current Price
ASI294MC Pro SONY IMX294 4/3" 10.7 MP Check Current Price
ASI071MC Pro SONY IMX071 APS-C (1.8") 16 MP Check Current Price
ASI128MC Pro SONY IMX128 Full Frame (35mm) 24 MP Check Current Price

All of the Pro model ASI color cameras include the DDR3 Buffer technology which results in faster data transfer speeds and reduces amp glow. Each one of these cameras requires 55mm of back focus between the image sensor and your flattener/reducer.

In the case of the Celestron 8″ RASA F/2, no field flattener is needed as this optical system is very flat to begin with. However, a new backfocus distance is needed between the camera sensor and the top surface of the lens group cell. To achieve the required spacing of 29mm for the RASA, I used a Starizona filter slider drawer to give me some added backfocus.

RASA backfocus distance

Making the Upgrade from a DSLR to a CCD-style camera

When I began using color CMOS cameras like the ASI294 MC Pro, I could no longer use the camera control software I did with my DSLR’s (Backyard EOS). Instead, I use an application called APT (Astro Photography Tool), which allows me to control every aspect of the camera from the cooling temperature to gain.

Upgrading from a DSLR to a CCD type astronomy camera like this is a big transition. For me, the hardest part was getting used to controlling the camera entirely with external software.

The change in image file formats (from .RAW to .FIT was also a bit of a hurdle early on. Luckily, DeepSkyStacker is well suited to stack and de-Bayer this image format into a high resolution .TIF file that you can process in Photoshop.

ZWO ASI294MC Pro Review

The two-stage TEC (Thermo-electric cooling) is perhaps the biggest difference and advantage a dedicated astronomy camera has over a DSLR. As you may know, noise is a big issue to deal with when taking long exposures at a high ISO. I’ve battled with noise for many years (and continue to do so) when processing my astrophotography images taken with my Canon T3i and 5D Mk II DSLR’s.

A cooled CMOS camera like the ASI294 MC Pro can cool its sensor down to 35 degrees below ambient. This results in images that are virtually free of thermal noise. I should mention that it’s important to understand that this means 35 degrees below the current temperature, so if it’s a hot 30-degree night, the camera will max out at -5 degrees.

APO refractor telescope

The ASI294MC Pro Camera attached to my Explore Scientific ED102 Refractor Telescope

Pixel Scale

The pixel size of the ZWO ASI294MC Pro is a great match for many of my astrophotography telescopes. The pixel size of the ASI294 is 4.63µm, which is in the middle of the road for the ASI camera lineup. For comparison, the ASI183MC Pro has a sensor with a 2.4µm pixel size.

So what does this mean for your astrophotography images?

In the amateur astrophotography community, a general rule of thumb is to use a pixel scale that is between 1.0 to 2.0 to be “well-sampled”. This is simply a rough guideline and should not be taken too literally. The math for calculating the pixel scale of a particular camera and telescope combination is:

pixel size (4.63) / focal length (550) x 206 = 1.73

When using the ZWO ASI294MC Pro with the Celestron 8″ RASA F/2, I have a pixel scale of 2.38 which some consider to be “under-sampled”. Theoretically, under-sampling can lead to blocky or pixelated stars in your image, although in reality, I have never known this to be a noticeable problem (in any of my telescopes).

Compare this to the Sky-Watcher Esprit 100, which provides me with a pixel scale of 1.73. The bottom line is, it’s worth calculating the pixel scale of your camera and telescope combo before making any big decisions. In my experience, the ZWO ASI294 is an extremely versatile choice for many telescope focal lengths.

lobster claw nebula

The Lobster Claw Nebula captured using the ZWO ASI294MC Pro and Radian Raptor 61.

Connections and Software

The camera is connected to my computer via a USB 3.0 cable. For the cooling feature, it also requires an external 12V power supply that does not come included with the camera. If you’re anything like me, you have accumulated a number of 12V adapter cables over the years.

To keep things organized and convenient, I now connect the power port on the ASI294MC Pro to the outlets on my Pegasus Astro Pocket Power Box. This means that the camera and telescope don’t have another power cable running to an outlet. It all rides atop the iOptron CEM60 equatorial mount.

The camera is controlled using APT, which required the appropriate drivers from the ZWO ASI website. Installing the driver is painless, and then the “ASI camera” selection will appear from the drop-down menu the next time you connect the camera to APT.

The cooling function is set using the “Cooling Aid” within Astro Photography Tool. It can take a few minutes to get the camera sensor to the temperature you want it. It’s best to get a head start on this process so you’re not waiting around when it’s time to shoot.

A One-Shot-Color Camera – Impressive Specs

I love how sensitive the SONY IMX294CJK sensor is on this camera. The dynamic range of this camera sensor is listed at 13 stops. This is even more than the legendary AS1600 camera from ZWO. This characteristic is thanks to the built-in 14bit ADC (analog-to-digital converter) unit on the 294MC Pro.

ZWO ASI294MC Pro Camera Specs:

  • Sensor: 4/3″ SONY IMX294 CMOS
  • Diagonal: 23.2mm
  • Resolution: 10.7 Mega Pixels (4144 X 2822)
  • Pixel Size: 4.63µm
  • Bayer Pattern: RGGB
  • ADC:14bit
  • DDRIII Buffer: 256MB
  • Back Focus Distance: 6.5mm
  • Cooling: Regulated Two Stage TEC

If you’re wondering what the difference is between the MC-Cool and MC-Pro cameras from ASI are, it’s the DDR3 memory buffer. For non-tech-heads (like myself) this basically means that the camera can transfer data faster and more efficiently. It also reduces amp glow because this artifact is primarily caused by slow transfer speeds.

Here is what the amp glow looks like on a single image captured with the ASI294MC Pro. The amp glow is completely removed after stacking the images with dark frames in DeepSkyStacker.

amp glow

Recommended settings for the ASI294 MC Pro

I find that the best camera settings to use with this camera are to set the gain at “unity gain” and an exposure length of 3 to 5 minutes. This, of course, depends on the deep sky target you are shooting, and the filters being used with the camera.

For example, using a narrowband filter such as a 12nm Ha, I would choose an exposure length of at least 5 minutes. I even shot some images that were as long as 10 minutes with this camera. The photo below shows the Rosette Nebula using a stack of 20 x 10 minutes exposures using the ASI294MC Pro and an Astronomik 12nm Ha filter.

NGC 2244 in Ha

Because the sensor is so sensitive, I can often find my deep-sky target in a 2-3 second exposure in live loop mode. This is usually with a strong narrowband filter in front, which is quite impressive. This makes framing the target much easier because you’re able to see the shape and orientation of the DSO (almost) in real-time as you adjust the telescope.

Taking flat frames with the ASI294MC Pro

I use 3 layers of white t-shirts when capturing flat frames with the ASI29MC Pro. I point the telescope towards the morning dawn sky with the t-shirts covering the telescope objective.

When the white t-shirt method isn’t cutting it, a flat field panel like the Artesky Flat Field Generator works exceptionally well. 

flat frame target ADU

Taking flat frames with the ASI294MC Pro using a flat field panel (Artesky Flat Field Generator).

I use the CCD Flats Aid tool in Astro Photography Tool to find the correct exposure to hit my target ADU (25,000). In my experience, the images are usually around an exposure of 0.03381 when using a gain setting of 120 (unity gain). This creates a flat field image with an ADU of approximately 25000.

I have heard that others have found success by using longer flat frame exposures, which can be accomplished by adding more layers of white t-shirts or with an adjustable flat panel.

Final Thoughts

If you compare the ASI294MC Pro vs. the ASI071MC Pro, you’ll find that the price is significantly more affordable for the 294. I’ve used both of these cameras (The ASI071 camera was the older non-pro “Cool” version), and the image results are remarkably comparable.

The biggest difference between the two cameras is, of course, the sensor itself. The sensor in the AS071 is a 16MP APS-C sized chip, while the ASI294 is a four-thirds 10.7 MP sensor. This changes the pixel scale of your images and thus the apparent size of the objects you’ll capture through your telescope.

For APO refractors in the 700-1000mm range, the pixel scale of the ASI294 MC Pro was the absolute perfect size for some of my favorite deep-sky targets like the Eagle Nebula and Pelican Nebula. I used a Starfield 0.8X reducer/flattener with this camera and the various refractor telescopes I used when imaging deep sky objects.

Deep sky astrophotography telescope

If you’re looking to upgrade your DSLR or current color astronomy camera to the realm of “cooled” CMOS sensors – my results with the ASI294 MC Pro should help you make a more informed decision. I highly recommend the ASI294 MC Pro camera if you are in the market for a color astrophotography camera with some serious power and versatility.

I hope you enjoyed this review! If you’d like to stay up to date with all of the future posts on AstroBackyard, please sign up for my newsletter.

Dumbbell Nebula

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