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Using a Sigma 24mm F/1.4 for Astrophotography

|Camera Lenses|0 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 lens options.

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.

Sigma 24mm F/1.4 Art Canon

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.

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

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. 

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Canon EOS Ra Review

|Camera|15 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|20 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|17 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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