By: Vlad Fedosov
The Celestron CGEM is quite a popular mount from what I gather. Rated at 40lb capacity, puts it into an interesting mid weigh category between mounts like the Celestron CGM and the Vixen/EQ-5 clones. My story with the CGEM started with the excitement of finally getting my Losmandy G11 mounted on a permanent pier in my backyard. The excitement was dulled when I found out that the mount was ever slightly too close to the fence and would not allow me to see the planets that happened to be very low in the sky in 2018. Luckily I was able to borrow a CGEM from my astronomy clubs telescope library. Let’s check out how it did.
I used the CGEM in my backyard to primarily observe the planets over a two month period. I used a variety of scopes on the mount but the primary instrument used was my Meade 127ed. I will start off by discussing how the bulk of the mount feels when fully setup. I have experience with both a lighter weight mount such as a Meade LXD-75(usually setup with a c8) and a heavier G11, both of which I was able to leave setup and carry out the back door full assembled(g11 with no scope or counterweights, LXD-75 with scope and counterweights). The CGEM fully setup weights a lot closer to my G11 then the lighter Vixen clone mounts. There is no way I would be able to carry it out setup with a light scope such as a c8 like I can with the LXD-75 mount.
Having established that it quite a bit heavier then the grab-and-go type EQ mounts I’m used to, I was interested to see just how stable it was. Setup with the long 5″ refractor stability was acceptable but honestly not impressively stable. After refocusing I would need to wait about 3 seconds for the scope to stabilize witch was a hair better than with the LXD-75 mount, but much worst then the g11 which is rock solid with the same instrument.
The overall mechanics and operation of the mount are satisfactory and I really do not have any complaints there. The CGEM again feels a lot closer to the LXD-75 here than the very smooth and premium feel of the g11. GOTO accuracy is about the average as compared to what I have experienced on other mounts and GOTO scopes. This, of course, varies from sample to sample. Another aspect of the mount that I did not like is that you need to turn on tracking from the menus every time you turn the mount on if not using the GOTO. Most other EQ mounts that I have used just had the tracking on all the time once the power was switched on. The tracking, however, is very smooth and I did not notice any jitters even while observing at high power.
Overall I had a good time using the CGEM to observe the planets. Would I buy one myself? I absolutely would not. Not because it’s a bad mount, but because for the weight of it you just do not get the stability that is expected. It’s just as much work to set up the CGEM as it is to set up the G11. I must stress that this is only important if you are using a mount in the same manner that I was. I like the ability to have it setup and be carried out in one piece. If you would break a mount down and setup every time then this is not much of an issue as any EQ mount is about the same amount of steps to setup.
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