I will mostly be observing in my backyard. Bortle 6 ish. Not sure how that impacts going with an 8 vs 9.25. I think EDGE will stretch my budget with minimal gains, to be honest so agree there.
I was leaning towards the CGX to help reduce future costs on an EQ mount. It's not often I get the green light to spend 4k + on a hobby so trying to get the big stuff covered so to last me the longest. If the CGEM II will handle the 8" OTA and not losing out on any features in the CGX, I'm all for saving the money.
A CGEM II will definitely handle a 8" OTA, but you'd lose a couple things:
- direct USB connection to the mount (with the CGEM it passes through the handcontrol's USB port instead)
- payload capacity (40 lbs VS 55 lbs)
The way you use it is quite similar, all Celestron EQ mounts share a common handcontrol, CPWI is compatible with all of them, both the CGEM and CGX have PPEC, and with a 8" OTA the tracking performance should be quite similar.
However, going with the CGX is totally respectable. It's a nice mount (but, again, a bit on the heavy side)... and an oversized mount never hurts (save your back and budget).
I started with the EVO 8 however, got concerned with EVO mount and spacing issues at the back. Plus I want an EQ should I want to go do some AP later with a different OTA. However, I am not familiar with guidescope/plate solving. StarSense was a feature I was leaning on because I'm in a bortle 6 area and I have a very obstructed view N, and NE and polar alignment may be difficult. I will need to look into plate solving further to learn more about that.
How is a guidescope + camera + ?? (~ $600) better than StarSense at $399 if they accomplish the same thing?
Also, "guide camera ($300)" -- Which guide camera do you suggest?
They accomplish the same thing, but Starsense is really limited in what it can achieve:
- it can't guide. By experience, once it's set up, autoguiding is really nice to have, even for EAA as you will certainly use long exposures at some point (almost everyone does: filters, faint objects, you name it)
- it won't do polar alignment (but as you have a limited sky view, that argument is maybe moot)
- it won't recenter your mount after a goto.
You can see Starsense as a nice helper tool for visual observers: it will align your mount with no additional electronics. But as you're considering EAA, which means having at least some kind of a mount-side computer (be it an ASIAir Pro/Plus or a fully featured PC), there are other software tools available that will make your life even more easier. NINA has a 3-star polar alignment routine that works really, really well when you have no view on Polaris. Sharpcap and ASIAir have a fast and reliable polar alignment feature.
As for the guide camera: a mono 290mini is the usual choice, while it lasts (Sony is retiring the sensor I'm told).
I planned to get ASI294MC non-cooled version around $699 I think. I also planned to get a motor focuser so I could sit in the house and fully control the scope.
That might be where I differ the most: really, get a cooled camera if possible.
I'm not saying one cannot do EAA with a non-cooled camera (I did for 2 years and I was happy with that), but the comfort you get with a cooled version is invaluable, all the more as the 294, while nice and sensitive and a perfect match to the long focal lengths of SCTs, has a lot of thermal noise. Believe me, you'll find yourself trying to capture 15s+ exposures in no time, and that's where a cooled version will shine.
I know, it's a tricky decision: there's always a better option, but you only have so much budget (and opportunity to spend it). Granted, all elements are important, but if I had to prioritize things for EAA, the camera would be first, followed by the mount, and the OTA would be last.
Edited by Clouzot, 26 October 2021 - 08:56 AM.