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Dedicated Astronomy Camera vs. DSLR

Save your money for the optics and the camera. After all a dedicated astronomy camera is the next logical step. Given that I’m dad of the century, my family gave me the ZWO ASI183MC Pro for Father’s day. Of course that was a great day, yet Covid-19 had other plans. For this reason, I waited several months to receive it and get first light. Finally I have gained a little experience so let’s compare it to my Canon T3i.

What is a Dedicated Astronomy Camera?

It’s all about capturing that H-Alpha signal in low light and since DSLR cameras filter red, it was time to change the game. Canon introduced the 60Da with a modified filter just for astrophotography and it didn’t disappoint. I’ve never used one but Trevor Jones from Astrobackyard can support you. Most nebulae emit significant amounts of H-Alpha light and the more you can capture, therefore the better the picture. Of course I can buy one of these cameras. Nope.

Now discontinued, other options were needed to fill this void. Bring in ZWO and QHY. Both companies design and manufacture cameras for the single purpose of taking pictures through a telescope.

Dedicated Astronomy Camera
ZWO ASI183MC Pro Dedicated Astronomy Camera

In essence, the dedicated astronomy camera is defined as a camera sensitive to a wide range of the light spectrum specifically for use on deep sky objects as well as solar system objects. OK that was a mouth full. Therefore these cameras can do it all and there are a lot of other technological advantages to boot.

Sensor Comparison

DSLR Camera
Canon EOS T3i
Dedicated Astronomy Camera

Comparatively speaking my Canon T3i has a CMOS sensor similar to the ZWO ASI183MC Pro. All subsequent metrics do not compare. First let’s compare the size of the sensors. The Canon is 22.3 mm x 14.9 mm in size. And it captures a cool 18 megapixels. While the ZWO camera is 13.2 mm x 8.8 mm in size. It too gathers a cool 20 megapixels. Here’s a comparison chart.

Dedicate Astronomy Camera vs DSLR Comparison Chart
Comparing a Dedicated Astronomy Camera with a DSLR

After all, consider the following, a smaller sensor means smaller field of view. That tells me that I have to take this into account when I choose my target and telescope. In effect, smaller targets with a high focal length telescope can be too small in the framing with the DSLR. Consequently choosing the ZWO camera may fit it perfectly in the frame.

How To Plan Your Shots

Astrophotographers are great at creating tools to assist in creating the best photo possible. In fact I use a site called Astronomy Tools. And one of the tools is an FOV calculator. It looks like this:

Not only does it help you with astrophotography, but also included are calculators for Visual and Binocular astronomy. In either case the user must choose the object in view. I will choose M42 for this example. Next choose the equipment. By and large the site’s database contains most telescopes and cameras. Simply pick from the list. Alternatively if it doesn’t you can add also. Here is what my framing would look like using both cameras on my Orion Astroview 6.

Framing Example 1

Comparison tools like this give you insight that you would ordinarily have to calculate on your own. In this case, the ZWO if perfect for the Running Man Nebula alone. While the Canon comfortable fits both in the frame. Let’s look at another example.

Framing Example 2

This time I changed to the Orion ST80 telescope. Chiefly important to see is that the Dumbbell Nebula is too small in the frame using the Canon camera. Here we will definitely frame it better with the ZWO.

My Dedicated Astronomy Camera Is Cooled

Because the Canon EOS T3i is not cooled, the sensor heats significantly up especially on summer nights. As a result, noise is a big problem for me. I cannot take photos higher than 800 ISO. On the contrary, my dedicated astronomy camera has a cooling fan.

Dedicated Astronomy Camera
View of Cooling Fan

The manufacturing specification says the camera can cool between 40 – 45 C below ambient. Meaning at 85 F or 30 C you can cool the camera to between -10 C and-15 C. In short the colder the outside temperature, the cooler you can keep the sensor. Concluding with a picture containing significantly reduced noise. In other words, you’ll be spending less time removing noise in post processing. Therefore keeping your signal to noise ratio high. In conclusion, this is the primary reason for choosing the ZWO camera over my DSLR.

Pixel Size Comparison

Surely capturing the most intricate details in any object is important to you as it is for me. When I moved away from my Google Pixel to the Canon DSLR I discovered how important details are in astrophotography. With this in mind, the chart above showed that the pixel size of the ZWO camera is almost half the Canon. An internet search emphasizes that larger pixels provide higher quality photos. Particularly in the area of noise. There’s a huge trade off, especially since we learned we can control noise by cooling the sensor. I have the choice to add cooling to the DSLR and may consider this for the future.

To emphasize the importance to detail. Cooling allows for a higher quality photo and a smaller pixel size increases detail in your photo. Below are photos taken with two ZWO cameras to highlight the difference in details. Click on the photos to read their article.

Sun Spot detail comparison

The smaller pixel size is more detailed verses the larger pixel size photo. This is a bonus when compared to my DSLR on the contrary, I believe it will be a different review when comparing similar cooled cameras.

What About QE And What Is It?

QE or Quantum Efficiency is a measure of the amount of light that passes through your optics and is used by the sensor. Who wants to have their telescope do a great job of gathering light and the camera only uses 40% of it? In light of my DSLR only using 40% of the light, I am happy to learn that this ZWO ASI183MC Pro uses 84% of the light. This is more than double what the Canon EOS T3i achieves. Another reason why I will prioritize the ZWO camera.

Dedicated Astronomy Camera Conclusions

Here are comparison photos of Jupiter that displays the differences between the cameras.

Canon on the Left, ZWO on the Right

Obviously, I’m still learning how to use this new camera, and even in learning I can see a significant difference in photo quality, and increased details. Hopefully all of the information shared is helpful to you. I recommend moving to a dedicated astronomy camera as you grow in this hobby. Good luck to you and remember that the sky is the limit only when your mind is unwilling to fly. Go beyond!

Kevin Francis

Kevin Francis is a Mechanical Engineer by day, amateur Astrophotographer by night who is taking his Google Pixel smartphone camera to new limits.