CGEM Review Part 4- Astrophotography

After getting the necessary equipment together and waiting for a clear night,  I finally got to try out astrophotography with my CGEM! I spent a lot of time yesterday getting my observatory prepared with some last minute touches. Soon after sundown, I was performing a polar alignment in preparation for imaging M42, the Orion Nebula. This would be my first target with the CGEM, Canon XSi, ED80, and autoguider. Shown here is the CGEM all ready to image:

I knew it was not going to be the best night for deep space astrophotography because of the full moon. But I wanted to at least try out the new equipment. M42 is a bright target so I hoped I could get decent results.

Canon XSi Setup

This was the first time that I got to use the new Canon XSi for astrophotography. I sold my Canon Digital Rebel (300D) which provided a lot of good photos with previous telescope setups. One thing I really like about the XSi is the EOS Utility that allows for remote imaging with the bulb setting. And, it uses the USB cable that comes with the camera so no need to purchase (or make) a special one. There is an automatic routine that lets you set the number of exposures, intervals, and exposure time and follows through automatically.

Focusing used to be a bit difficult in the past but now I have a Bahtinov Focusing Mask. This thing makes focusing incredibly easy and fast! I bought an inexpensive one here at (thanks to a tip from Jeff Turner over at DaltonSkyGazer). I just laid the mask over the end of the ED80 and did a quick exposure with the XSi to see the diffraction pattern. A couple tweaks of the ED80 focusing knob and it was perfect. I hoped that it would show up in live preview, but for some reason it did not. I’ll have to figure out how to use live preview for focusing with the mask next time.

Once I got the XSi ready to go (focusing, centering of M42, etc.) I got the autoguider going.


Autoguiding with the CGEM

I have to admit, this is the first time that I have ever done any guiding! I used to do a precise drift alignment with my LX200 and keep my exposure times to a minimum. I had to sort through a lot of frames to find ones that were suitable to use for stacking.

I recently purchased the Orion Awesome Autoguider Refractor Telescope Package. This is becoming a popular solution for guiding due to its low-cost as a complete system. It comes with a ShortTube 80mm refractor, Starshoot Autoguiding Camera, dovetail mounting bar, and rings.

Using this system with the CGEM was rather easy. One cord plugs into the autoguiding port on the CGEM and the other cable plugs into the USB port on the computer. It runs off of a software program called PHD Guiding. There’s just a few simple steps to go through before it starts to guide.

Overall, the performance of the autoguider on the CGEM was excellent. Once it locked onto the guidestar, I didn’t have to worry about M42 drifting. I was able to use all of the frames that I shot through the XSi. In fact, each frame looked identical. All of the stars were in the exact location from frame to frame and all were round. This was very exciting! I hope to do a write-up of the autoguider soon. It is so simple to use and makes a big difference in the outcome.

More information: Orion Awesome Autoguider Refractor Telescope Package.
The only part of the autoguiding process that could have been better, was the calibration time. This took awhile! It took about 15-20 minutes for the calibration to complete. I’m wondering if it has something to do with my remote setup though. I’m running everything in my observatory on Cat. 5e cabling (underground) and using USB over Cat5e adapters. Unfortunately, they are USB 1.1 adapters instead of faster USB 2.0. I need to upgrade to the faster adapters eventually.

Capturing M42

It took me a few hours to get everything going before I could actually begin imaging. I was dealing with new equipment, some technical snags, and at one point in the night, complete cloud cover! Furthermore, there was a full moon and M42 was about to set. So I only had time for a few shots with the XSi. I managed to get 12 light frames at 60 seconds each and 12 dark frames for calibration. I was determined to have something to show for all my work through the day and night. It was almost 3:00 am when I started shutting things down. Here is the resulting image (click to enlarge):

Things should go smoother as I get more experience with this equipment. Next time I hope to take longer exposures and more of them. Look for more information as everything unfolds. So far the CGEM appears to be a nice platform for astrophotography. I am seeing some excellent photos coming from this telescope from the astro-imaging community. I hope to show the same results soon!

Update: Image from 2-2-2010!

Click Photo to Enlarge

Took more exposures this time. Here’s the details:

16 x 80 seconds at ISO 1600

10 x 60 seconds at ISO 400

Software Tip

I tried a free stacking program called DeepSkyStacker for this image of M42. I thought it was SUPER easy to use and it worked very well! You can download it here. Enjoy!

Hand Control Extension Cable

Now available through AstroPhotography Tonight! Extend your NexStar hand controller another 7, 14, or 25 feet! Click here for details.


  1. Hi Ray,
    Really love the picture you’ve made. It looks like the CGEM and the Orion autoguider are a super combo. Looking forward to see more pictures and reviews.

    Keep up the good work!


  2. Hey Robert!

    Thanks! I can’t wait to get more time under better skies. I think the Orion autoguider and the CGEM are going to work well together. I want to see what happens with longer exposures like 4-5 minutes. I’ll be sure to post the results. Thanks for looking.

    Ray Shore

  3. Very Nice Ray! I am glad someone had a break in the weather in the CGEM groups. You may try taking your iso up to 1600 when focusing on a star it may help.

    I am hoping to have a break in weather and work soon. The day is coming I can feel it. I still have yet to try the autoguider and new Edge ota out.

    My new greenscreen and stands arrived today. Trying to tackle some more clutter in the house I should have some time if weather is bad to mess around with that and the video cam again soon.

    My first night out I am hoping to first test out the autoguider with the DSI IIIC which I am comfortable with then if weather cooperates I will try imaging with the new 450 Xsi. I would like to get some through the new edge plus also some images done with my 80mm. Fingers crossed for good weather soon.


    J. Turner

  4. Great image, Ray!

    Looking forward to seeing what the CGEM and the 9.25 Celestron can do. Hope you can image something with that setup before I place my order for the 11 inch Edge HD by the end of March. I have been weighting the alternative of the 9.25 Edge HD and buying the skywatcher 80ED at the same time. Tough decision, but your images show that the 80 is a very good scope indeed.


    J. Auger

  5. Jose,

    My intent with the 9.25″ was for planets. I like imaging deep space objects with a shorter focal length scope like my ED80. I could try to image deep space objects with the 9.25″ but I should probably get a focal reducer first. Otherwise, f/10 might not be a good match for the Canon XSi sensor.

    I’m working on a better M42 photo tonight. I’m getting the best looking skies I’ve seen in a long time. I’m getting better frames this time around. I hope to post the image tomorrow.

    Ray Shore

  6. Jose,

    One more thing. Be looking for results from Jeff Turner. When he gets some clear skies, he will be imaging with his 8″ EdgeHD and DSI IIIC. See his comment above.


  7. yeah yeah.. make us cry .. we’ve been waiting for clear skies for ages here in Holland and you’ve got the best looking skies seen in a long time 😉
    Now show us what you can do with that Celestron set !!


  8. Yeah, but I’ve been waiting forever for the little bit of clear skies that I did get Lol. I was able to take advantage of them and have a pretty good photo of M42 that I’m working on.

    Ray Shore

  9. Jeff Turner

    Ray that second shot rocks!!! Awesome job. I am freezing my butt off right now xsi is set to grab 8 pics at 5 min exposures on m66. Had issues earlier with 20-30mph winds with 14F weather. As you know could not find ac power adapter for xsi but i am on backup battery hope to get these exposures done and do my dark tonight…………..Brutal weather many mishaps as expected in the cold and new gear but PHD guiding very well so far….nice round stars across whole field of edge 800 ota on cgem. Only hope battery lasts right now and clear skies.



  10. Jeff,

    Those were brutal conditions you were dealing with last night. You wanted m66 badly! That’s what we do though. I froze the other night trying to get that first M42 photo.

    I hope your image turns out nice. Will be interesting to see how well the EdgeHD performs!

    Ray Shore

  11. Ray,

    The only word that came to my mouth when I saw the second image was AWESOME!!! Great, really great image. Pinpoint stars, clear definition of the nebula, good amount of nebulosity, stars in proximity to one another can be clearly resolved. Congratulations.


  12. Jose,

    Thanks for the nice comments! I am really pleased with this setup. I feel like I can push it a lot further in terms of exposure length. I had to be careful since I was running off the XSi battery for these shots. I have an AC adapter on the way though so I can take longer exposures and WAY more of them. I can’t wait for another clear night to try some more things. I really appreciate your input 🙂

    Ray Shore

  13. Ray,

    That second pick is very nice. The detail is outstanding!! Very sharp focus and great post processing work! I am taking baby steps at post processing right now just getting grasp of it all. Will be working with the Adam Block video to improve my post processing skills. Last night was one tough night but I had a few positves #1 first light of new edge 800 OTA, Autoguided for first time in my life, and used the Xsi DSLR for first time. This was also first night out with the new side by side setup. I learned a lot of lessons. I expected some headaches with the new gear and also with the cold weather. I come out of the session with some lessons. After seeing how things went I can not wait til the warm weather comes where I am able to spend more time direct at the scope. I do wish that Celestron would hurry up and release the focal reducers for the new Edge HD ota’s. Keep the pics coming!

  14. Jeff,

    That was one heck of a night out with your CGEM! It seems like there’s lots of SNAFU the first couple of times with a new system. My first shot of M42 with my new setup didn’t come easy. I didn’t get to snap shots of it until it was about to set at 3:00am! But the second time around, I got to start imaging fairly quickly because some things were lined out. I’m with you though, can’t wait for a little warmer weather!

    Ray Shore

  15. Ray,

    Looks like there could be some decent weather coming up. I am looking at two whole nights of imaging now. I hope the winds stay low. The temps are not bad looks to be mid-upper 20’s which is like a heatwave………I will be dealing with moon but not til between 11pm and Midnight. Will be setting up at friends observatory. I plan on doing quite a bit of imaging with the 80mm, and will do some imaging with the DSI III this time throught the edge ota for some comparison shots. The pixel math does not work out well with the Edge OTA unless a focal reducer is used.


    Jeff Turner

  16. Hi,

    I have just started studying the subject of astro photography and I may sound like a complete idiot here. In your fantastic shot from 2/2/2010 of M42, is this a full resolution image you have uploaded or has it been cropped and / or compressed?

    The reason I am asking is that my long term goal is to print portrait size images of object like M42 and similar, and I would like to know what type of hardware you need to do that.

    1. AstroPhotography Tonight

      Hi Rick,
      No worries, your question is a good one. I did crop and reduce the image size so that it would load fast. The original was probably 4290 x 2856 pixels. I used my Canon XSi Digital SLR for the photo. I hope this helps 🙂

      Ray Shore

  17. Hi Ray,

    I’ve been doing searches for the CGEM mount & found your reviews – they are brilliant.

    I’m on a basic Skywatcher EQ5 mount.

    Have been leaning towards the CGEM purely for the special alignment (as I can’t see Polaris). I think your reviews have confirmed that this is the one I need. Also as it’s Astrophotography I want to do.

    Can I ask – how do you find it now ?

    Thank you,


    PS – your pictures are great

    1. AstroPhotography Tonight

      Hello Viv,
      Thanks for the nice feedback! I still do like my CGEM mount. In fact, the last time I did astrophotography with it, I turned out a photo that I feel is my best work so far: I’ve gotten to where it doesn’t take long at all to set it up. The goto is amazingly accurate and it works well with the Orion autoguider. I hope to do some more imaging with it soon!

      Ray Shore

  18. Robert Zelonis

    I spent this afternoon researching any web site that included the words “Orion Starshoot Astroguider” and ended up on your site again. Ray, your experiences are very encouraging. Now, I must decide between the 80 mm. version or the mini 50 mm. one (an individual mentioned that the mini version gave him more stars to guide on). Your other responders have answered a question I’ve had: Can the CGEM mount be used during extremely cold weather? Apparently “yes”, at least as low as the 14 degrees that someone mentioned. It’s been as low as 1.4 degrees F. here in my part of New Hampshire. Did any of your responders and/or you have to change the lubricants in the CGEM mount?

    1. AstroPhotography Tonight


      Welcome back! I’m thinking about getting the mini 50mm guide scope after hearing how well it worked for my good friend Jeff Turner over at He says that there are way more stars to guide on. Good to hear that others are using their CGEM in extremely cold weather. Mine has always worked no matter how cold it got. I’ve been out many times when it was well below freezing. I haven’t heard whether others have changed the lubricants or not. I have not done that myself yet.

      Ray Shore

  19. Ray,
    Have you tried really long exposures, up to 10 minutes or so, with the CGEM?

  20. I have had great success down to -3F with the CGEM. It is definetly worthwhile to get the hypertune kit, or at minimum replace the factory grease with a grease of higher quality. From the factory the grease job was quite horrible, blotchy.

    I have been using the mini 50 now, I was using the 80 mm awesome guider, I am impressed with the mini 50 in star choices, and how well it guides with these stars.

    If the weather would cooperate around my work schedule I am hoping to have some images at some point with new camera. T2i.

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