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Astrophotography with a DSLR Camera and Small Telescope

|Telescopes|15 Comments

This week, I returned to my roots and enjoyed some deep sky astrophotography using a DSLR camera and small telescope. Don’t get me wrong, dedicated astronomy cameras and heavy duty mounts are great, but my latest imaging session in the backyard was a breath of fresh air.

In this post, I’ll share my early results with a new compact refractor telescope, the William Optics Zenithstar 73 APO.  I’ve managed to collect some exposure time on a number of deep sky objects using a crop-sensor (modified) DSLR.

My experiences with the Z73 have reminded me how much I enjoy deep sky imaging through a wide field refractor with a DSLR. This is where my astrophotography journey began, and it has not lost its appeal over time. Not one bit.

AstroBackyard

Returning to my roots…

The cooler nights of fall have allowed me to begin using my DSLR camera again for astrophotography. The overnight low has dropped to about 8-10 degrees C, a welcome relief from the scorching, humid nights of summer.


These conditions not only make the longer nights more pleasant outside, but they offer up better conditions for photography as well. There is less moisture in the air and the electronics in my DSLR are able to function properly without becoming dangerously hot.

The temperature of the sensor in my Canon EOS Rebel T3i has been hovering around 25 degrees C during my imaging sessions, which is still warm enough to produce a quite a bit of noise. A 5-minute exposure at ISO 1600 is a lot to ask of a camera designed for daytime photography.

But enough about my old DSLR for now, let’s get to the fun part. (My new telescope). To stay up to date with my latest endeavours in deep sky astrophotography, please subscribe to my email newsletter.

DSLR camera and telescope

The William Optics Zenithstar 73 APO

The William Optics Zenithstar 73 is a compact doublet APO refractor designed specifically for astrophotography. Owners of full frame DSLR cameras will appreciate its 45mm diameter illumination circle for edge-to-edge images.

After picking up the Z73 from the William Optics booth at NEAF, I am finally using this premium refractor for astrophotography at home in the backyard. A series of rained out camping trips and even a clouded-out star party put a lid on my summer plans to use this portable APO under dark skies.

This compact and lightweight apochromatic doublet refractor has a lot going for it, including an ultra-wide field of view and high-end Ohara FPL-53 objective lens construction. I was fortunate enough to receive a complete package that includes the dedicated Flat73 field flattener, 50mm Guide Scope and more.

When asked which color I prefer, I had to keep the tradition of white and gold alive to match the Z61 APO and FLT 132 refractors. This “big brother” to the Z61 uses a new mounting ring and guide ring design, that match the gold Vixen-style dovetail bar.

Z73 Guide Scope Rings

After taking the Zenithstar 73 out of the neatly packaged soft carry case, the first thing I did was separate the guide scope rings a notch to provide a more balanced hold of the 50mm guide scope. I removed the Rotolock (which is an added accessory from the standard package) to thread the dedicated field flattener in for astrophotography.

A great place to thread a 48mm filter (such as the Baader Moon and Skyglow filter pictured below), is on the Flat73. Then, you can attach the field flattener to the telescope with the filter inside.

Flat73

I must say, I was spoiled with a totally complete package that included all accessories. These are additional items to consider when calculating the overall price of the package. The accessories for the Zenithstar 73 include:

Optional accessories:

  • Soft carry case
  • Flat73 1:1 Full frame flattener
  • 2” Rotolock with M63 threads
  • 50mm F/4 Rotolock Guiding scope
  • 48mm T mount for Nikon or Canon

What’s nice is, William Optics outlines everything you’ll need for a deep sky astrophotography system – and you can order it all together. You don’t need to go searching for field flatteners or guide scope rings that will fit your telescope. Astrophotography is the number one priority behind everything William Optics makes.

FPL-53 flourite glass

William Optics Zenithstar 73 APO Specs

Glass Type:FPL-53
Focal Length:430mm
F-Ratio:F/5.9
Weight:5.5 Lbs
Retracted Length:310mm
Focuser:2.5" Rack and Pinion
Dew Shield:Integrated
Mount:Vixen-Style Dovetail

 

The Zenithstar 73 APO is available at Ontario Telescope

 

Deep Sky Images from a City Backyard

The timing of the full moon and ever-present glow of my urban sky meant narrowband filters were the obvious choice. Even with a color DSLR camera, astrophotography can be enjoyed a great deal more with a simple clip-in ha filter.

The primary DSLR I use for deep sky astrophotography is an old Canon EOS Rebel T3i that has had the full spectrum modification performed. To compare it with a dedicated astronomy camera or CCD, you could consider it to be an un-cooled one-shot-color camera.

DSLR Ha filter

An Astronomik 12nm ha filter was snapped into the body of my APS-C sensor Canon T3i for the following images. With the Flat73 field flattener in place, it should come as no surprise that the stars in my image were recorded as pinpoints top the very edges of the image.

Sadr Region in Cygnus (Butterfly Nebula)

The Butterfly Nebula (IC 1318) is a rich emission nebula region in the constellation Cygnus. It is part of a much larger complex of gas and dust residing in the Sadr region. The photo below shows off the wide field of view and crisp stars you can expect when using an entry-level DSLR with the Z73.

Butterfly Nebula in Ha

I captured roughly 2 hours worth of exposure time in Ha using my Canon T3i through the Z73. The images are free of star-trailing and elongated stars thanks to the accurate tracking of my Sky-Watcher HEQ Pro Synscan mount.

This mount is a twin to the Orion Sirius EQ-G GoTo, which I often recommend to beginners as a robust, astrophotography-worthy mount for a setup like the one shown on this post. With a sound polar alignment routine, this equatorial mount can consistently provide sharp images of 5-minutes or much more. (The longest I’ve shot was 10)

The iOptron CEM60 center-balanced mount I used for the past 12 months has been returned to its rightful owner after a generous extended loan from Ontario Telescope. Luckily, the 5.5-pound William Optics Zenithstar 73 is nowhere near the limits of the HEQ5’s payload capacity.

GoTo Telescope Mount

The Heart Nebula in Cassiopeia

Next up is a rather dynamic looking nebula in Cassiopeia known as the Heart Nebula. As you can see, this massive target fits within a single field of view using the Zenithstar 73 with a crop-sensor DSLR camera. The F/5.9 aperture of the Z73 provides a healthy balance between light gathering ability and sharpness.

Heart Nebula in Ha

Both the Butterfly Nebula and Heart nebula images were produced using 5-minute image exposures at ISO 1600. Astro Photography Tool was used to automate the image captures, with PHD2 guiding helping to accurately guide my HEQ5 mount during each sub.

Dithering between each image and stacking multiple light frames helped to improve the overall signal to noise ratio in the images. The individual light frames were very noisy, but using dark frames in the stacking process (DeepSkyStacker) can really help to correct this.

Why I love a DSLR Camera and Telescope Setup Like This

For the type of astrophotography I’m most interested in these days, it’s hard to beat the photography opportunities available at the 400-500mm focal length. At 430mm and F/5.9, the Zenithstar 73 fits the profile of the ultimate wide field APO for deep sky.

I’ve repeatedly mentioned how much I love to use APO refractor telescopes, and I believe that they offer a better user experience and more consistent astrophotography results than any other telescope type.

Sky Watcher HEQ GoTo Mount

Telescopes that offer a longer focal length (of 1000mm or more) are great for small DSO’s and galaxies, but deep sky objects that cover a large area of sky such as the Heart Nebula are impossible to photograph with a DSLR without creating a mosaic.

One of the advantages of having a wide field of view is the ability to capture multiple deep sky objects in a single shot. It allows you to get creative with the framing of your target next to a star cluster or some interesting nearby nebulosity.

The photo opportunities are endless, and I you may find a lifetime of ideas before feeling the need for a telescope with an increased focal length.

Image Processing Narrowband Images from a DSLR

Here is a look at the individual light frames using the Canon T3i through the Zenithstar 73. The images have a red cast because of the strong narrowband filter that was used (h-alpha). I have registered and stacked the images just as I would with a color image in DeepSkyStacker.

light frames

Reviewing my RAW images in Adobe Bridge

DeepSkyStacker

For the Heart Nebula, I’ve got about 5 hours of total integrated exposure time. This is two nights worth of shots that I’ve separated into their own tabs in DSS. I captured matching dark frames of the same temperature, and also bias and flat frames to help produce the highest quality stacked image possible.

Extracting the Red Channel from an RGB image

The trick after that is – to extract the red channel with the strongest signal in Photoshop. Have a look at the difference in the image quality of the red channel alone vs. the full RGB image with weak Green and Blue channels.

channels in Photoshop

Notice the difference in signal from the red channel to blue when using a 12nm h-alpha filter

I copied the red channel channel out to a new image canvas, and processed it using many of the same techniques as a traditional deep sky image such as minimizing stars, a curves stretch and a bit of noise reduction. This greyscale image can then be added to existing color data, or become a part of a complete narrowband project that include SII and OIII.

For now, I’ll just enjoy the black and white image in good old Hydrogen Alpha.

Final Thoughts

It felt great to use my DSLR camera for some astrophotography again. I began my journey many years ago with a camera and telescope like this. If you are a beginner thats thinking about taking the plunge into deep sky astrophotography – I think you should go for it – and a setup like this is likely the best way to get started.

Next, I’ll shoot some broadband color images using a full frame DSLR with the Zenithstar 73 to really take advantage of the fully illuminated image circle. The Sky-Watcher HEQ5 has proven to be a reliabe GoTo mount over the years and continues to deliver incredible results for me. I look forward to more sessions like this in the coming weeks as the longer, cooler nights usher in the new deep sky targets of Fall.

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The ultimate astrophotography target for your DSLR and telescope

|Nebulae|7 Comments

It’s very exciting to know that the night sky is full of galaxies, nebulae and star clusters to observe and photograph.  The great Andromeda Galaxy, the glimmering Pleiades, and the vibrant red California Nebula are all jaw-dropping astrophotography subjects.

Astrophotography with a DSLR and telescopeBut what is the best way to capture these amazing deep-sky objects?

The followers of this blog know that I am all about astrophotography with a DSLR and telescope.  This is a popular deep-sky imaging setup and is capable of some incredible results using affordable equipment that can often be purchased used.

A DSLR camera is a perfect option for beginners as they are much more user-friendly than a dedicated CCD astronomy camera.  In the post below, I’ll give you the ultimate astrophotography target for your DSLR and telescope.

I use a Canon 600D DSLR and an Explore Scientific ED102 CF telescope.  View my complete setup.

An amazing year of Astrophotography

As we approach the end of 2016, I would like to thank everyone who has connected with AstroBackyard this year. Whether it was a YouTube comment, retweet, or Facebook like, I really appreciate the support.  I’ve connected with beginners, seasoned veterans, and everyone in between this year. I hope you were able to get outside and partake in some astrophotography with your DSLR and telescope this year.

AstroBackyard - DSLR Astrophotography


As you learn more about astrophotography, it’s almost certain that you will want to revisit previous imaging projects.  The lessons learned during each and every night out with your DSLR and telescope make you a more efficient and organized astrophotographer. As a beginner, my goal was to photograph as many galaxies and nebulae as possible.  Equipped with more tools and knowledge, I am now taking a second look at some of best deep-sky objects the Universe has to offer.

Orion constellation

The Orion constellation from my backyard

As for my latest astrophotography project, I’ve moved on from my Horsehead nebula photo for the year.  Not that it couldn’t benefit from more time and processing, it’s just that I shared the photo so much that I thought it would be best to shelve the project for now and complete it next winter.  This project helped me hone my skills of combining narrowband data with color images, as seen in my latest video tutorial.

I have now started pointing my telescope towards the alluring diffuse nebula known as Messier 42.  The glowing Orion Nebula is in prime position for imaging over the next month or two.  I have photographed M42 many times over the years, but since then I have made many advancements I made in terms of both equipment and technique.

With my telescope’s relatively wide focal length (714mm), I can include the Running man nebula (NGC 1973, NGC 1975 and NGC 1977) in the same frame. I added a modest amount of data using my old DSLR and telescope (Canon Xsi and ED80) to an earlier version of Orion last year, but not nearly enough to do it justice.

Why I’m photographing the Orion Nebula all over again

My previous version of the Orion nebula was shot with an 80mm telescope (Explore Scientific ED80) and a Canon Rebel Xsi (stock).  The image I produced consisted of RGB data only (No H-Alpha), and was lacking the rich color that astro-modified DSLR cameras can produce.

Orion nebula using a DSLR through and telescope

My 2015 version of the Orion Nebula

Ways to improve my Orion Nebula image:

  • The Canon T3i has a higher resolution than the Xsi
  • The Canon T3i camera is modified (IR cut filter removed)
  • I can add narrowband h-alpha data and combine it with RGB
  • The ED102 telescope has an increased focal length and light gathering ability

A new astrophotography project begins




On Thursday, December 22nd, I began my latest astrophotography project with my DSLR and telescope.  I have a new favorite spot in the backyard that offers the widest possible window to the sky when aiming at M42.  Stellarium was helpful in planning this position for this particular time of year.

From my location, clear nights are few and far between in the winter months.  Obtaining enough data (5 hours+) to process the image to its full potential will be a challenge.  The final image will likely have much more Ha data than RGB.  The nights leading up to, and during the full moon are more commonly clear.

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M42 – A rewarding astrophotography target for beginners

New to using a DSLR and telescope? Try Orion!

Beginners are drawn towards the Orion nebula as an astrophotography target, and for good reason.  The bright color and intense details of this object can be captured even in very short exposures.  When shooting with a DSLR and telescope for the first time, focus and proper tracking are some of the biggest hurdles to overcome.  Fortunately, M42 is very forgiving in terms of both focus and tracking.

Focus

The bright stars that populate the area in and around the Orion nebula are perfect for adjusting focus and framing.  Many deep-sky objects are very dim, with no bright stars within the same field of view.  This can make focusing and framing the target a nightmare.  I like to use the stars in the Trapezium to achieve the best possible focus while using my Cameras live-view mode, or on BackyardEOS.

Framing

The stars in the Sword of Orion are a great help when it comes to aligning your image.  Even better than that is the fact that the overall size and shape of the nebula is revealed in short exposures (5 seconds).  This makes capturing test frames and making adjustments much easier.  This is not the case when shooting a faint reflection nebula such as the Witch Head nebula!

Tracking/Guiding

Beginners usually need time to fully utilize their telescope mount’s tracking and autoguiding abilities.  The longer the exposures, the more evident poor tracking becomes.  Luckily for beginners, an impressive photograph of M42 is possible using multiple exposures of 1 minute or less!  This target is just begging you to capture it!

Multiple exposures for more detail

The bright core of the Orion Nebula requires very short exposures to properly document the area.  To capture the Trapezium without over-exposing the image, I shot several 5-second subs at ISO 800.  I also set BackyardEOS to shoot a series of 30-second subs to capture the mid-tones and slightly less-bright areas surrounding the core.

Here are the totals from each series of shots at lengths of 5, 30, and 180 seconds at ISO 800.

  • 180″ – ISO 800 – 1 hour 9 minutes (23 frames)
  • 5″ – ISO 800 – 1 min 40 sec. (20 frames)
  • 30″ – ISO 800 – 5 min. (10 frames)

I registered and stacked each of the image sets in Deep Sky Stacker, and processed each of the files separately.  Once each image file was processed to maximize the intended level of detail, I blended the images together in Adobe Photoshop using layer masks.  This can be a difficult process, as this can sometimes lead to unnatural looking and/or flat looking deep-sky objects.

Here is the current state of my Orion Nebula image, using the short exposures in the core:

Orion Nebula with a DSLR and Telescope

The Orion Nebula – Early version using layer masks

As you can see, some of the faint outer nebulosity has been captured, yet the core of nebula is still well exposed without clipping any of the data.  In comparison, have a look at the stack of 5-second exposures at the exact same scale from the same imaging session:

Orion short exposures

A stack of 5-second exposures on the Orion Nebula

Using layer-masking in Adobe Photoshop, we can merge the data from all 3 image sets to reveal all of the details of the Orion Nebula in a single image. As I said earlier, this process can be difficult to master and takes time and patience to utilize properly.  If done properly, the nebula will look natural and full of detail.  I’ll provide updates along the way as I tackle this winter astrophotography project from the backyard.

Cold, long nights with my DSLR and telescope

Despite what the frigid winter temperatures do to our bodies, your DSLR will produce images with less noise in the cold!  The nights are also extra long, which means the potential of longer imaging sessions.  So fill your thermos will a hot drink, it’s going to be a long night. If you need me, I’ll be in the backyard.

Cheers, and all the best in 2017!

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Astrophotography in the City

|Backyard|1 Comment

Saturday Night Under the Stars

Astrophotography in the City

Last weekend I posted a new video to the my YouTube channel titled DSLR Astrophotography – A Night in the Backyard with my Camera. It is now Early-April, and we are in what amateur astrophotographers call “Galaxy Season”, as we transition from the Winter Constellations like Orion and Taurus, to the Summer Milky Way objects.  In between, there are some fantastic deep-sky objects to observe in the Spring Constellations Leo, Coma Berenices and Bootes.

The forecast called for clear skies on that crisp, cold Saturday night in Southern Ontario, and I was ready to image some deep-sky objects with my camera and telescope.  After a late dinner, it was a race against the clock to photograph my first subject of the evening, the Waxing Crescent Moon. If you want to jump straight to the video, you can find it at the bottom of this post.

Live-View DSLR Through a Telescope

Using the Canon 70D’s live view screen for telescope observing

Crescent Moon Astrophotography

 

I barely had time to get the beautiful Waxing Crescent moon into my telescope’s eyepiece before it became obscured by the surrounding trees in my neighborhood!  I shot a live-view video of the moon (with Earthshine visible) with my Canon EOS 70D DSLR through the telescope.  This may be of interest to anyone wondering what the view is like through an 80mm refractor telescope.  You need an adapter to attach the camera to the telescope, which you can buy online here.

After I focused the Moon and experimented with different ISO settings and exposure lengths, I snapped a couple of shots before moving on with the rest of my night.  You can have a look at the equipment I use for astrophotography here.

 

Earthshine Moon

The sky from my backyard

Next, I wanted to provide some examples of the dark-sky quality from my backyard.  Living in the central part of town has its advantages, but dark skies are not one of them!  I experience heavy light pollution from all directions.  This makes using a light-pollution filter on my camera necessary for long exposures.  Currently, I use the IDAS LPS clip-in filter on my Canon Rebel Xsi DSLR.  This allows to me to capture exposures of up to 5 minutes from my backyard.

 

Astrophotography in the City

The night sky from my backyard on April 9, 2016

 

The Big Dipper Asterism

Looking towards the Big Dipper in Ursa Major

Deep-Sky Target: Edge-On Spiral Galaxy in Coma Berenices

NGC 4565 – The Needle Galaxy

Once the moon had set, I promptly prepared my deep-sky astrophotography rig for a night’s worth of photons on my photography subject.  I settled on NGC 4565 – The Needle Galaxy because of it’s size, magnitude, and current location in our night sky.  The Needle Galaxy is an edge-on spiral galaxy that resides about 30-50 million lights years from Earth.  This handsome galaxy is the current photo in my 2016 RASC Observer’s Calendar hanging in my office at work, perhaps that is what gave me the idea!

Astrophotography in the City - Needle Galaxy from my backyard

NGC 4565 – The Needle Galaxy

Photographed on: April 9/10, 2016

Total Exposure Time: 54 Minutes (18 x 3 Min. Subs @ ISO 1600)
Mount: Sky-Watcher HEQ-5 Pro
Camera: Canon 450D (modified)
Telescope: Explore Scientific ED80 Triplet Apo

Guided with PHD Guiding
Stacked in Deep Sky Stacker
Processed in Adobe Photoshop CC

This interesting NGC object shows up rather small in my 80mm telescope, as many galaxies do.  A larger telescope with a focal length of 1000mm or more would be a better choice for this DSO.  I also had a bit of a challenge evening out the background colour of this image.  Flat frames would have made this issue much easier to deal with in post-processing.  With just under an hour of exposure time, it is safe to say that I will need to add more time to this image to bring out the colour and detail.


AstroBackyard on Youtube

I am completely blown away with the response to my YouTube Channel has received.  Thank you to everyone who has subscribed, I look forward to many new astrophotography videos in the future!

Beginner Advice:

What’s the best telescope for astrophotography?

Which camera do you recommend for beginners?

Astrophotography Settings and Tips

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