CGEM 925 HD Computerized Telescope
- Product Review (submitted on March 29, 2012):
I've had a Dobsonian for more than two decades and have used the 8" Celestron scopes that we had for labs that I taught in grad school. I now teach astronomy and wanted a scope that could produce wide-field images I could use in my lecture, as well as give me enough practice as an astrophotographer to be comfortable teaching a course on it. When I compared all my options with the personal budget that I had available, this was the model I got. I've shot images at f/2.3 with Hyperstar all the way through f/30 with a 3x Barlow. The optics are very good. Even after removing and replacing the secondary a couple dozen times, I still get nice, round stars when I use the scope visually. The polar alignment routine that is built into the CGEM works very well. Shooting at f/2.3 and with no guiding (just polar alignment), I can take exposures of 150 to 180 seconds before noticing the stars going out of round a bit -- that's with no PEC activated. The mount is heavy enough that I can still image with a breeze blowing. That stability was necessary when I was shooting from the Eastern Sierras, and I think my image of the Orion Nebula from that session demonstrates this feature well. Portability was another concern for me. I have a compact car, but am able to get the scope, mount, tripod, guidescope, etc. to fit in the trunk and back seat, and still have room for tent camping. The next upgrade I am considering is not the scope or mount, but a larger chip camera to take advantage of the large, flat field the Edge HD optics provide. With Hyperstar and my 1/3" chip camera, I was able to find asteroid 2005 YU55 when it passed by, and the mount allowed me to keep it in view for two hours to share with my students.
I agree with the other reviewer that a USB connection to the hand controller would be a good addition. Also, some teflon bearings between the mount and the tripod would make polar alignment much smoother.
Overall, this has been a terrific set-up for getting a working understanding of astrophotography. I look forward to many more clear nights of imaging with it.