CGEM 925 vs 925 Edge

[Cody (Cody)]

I've been tossing up between these two and reading a lot of comparisons on the forums. While it seems that some people can't see any difference, most believe the Edge is better visually and especially good for AP.

However I can also see that you can buy the official Celestron Focal Reducer for the 925 quite cheaply, whereas the Edge version has been promised for 4 years now and still has not been released (which indicates it may never be released?) There are two third party versions that are very expensive and with varying reviews and compatibility (I didn't keep notes but seem people had to switch back to their standard focuser, others had issues with being unable to use some accessories because of spacing).

Like everyone I've been wanting to get a scope that is going to last and gives me options; the SCT fits the bill because of f/10 plus f/2 if I go HyperStar down the line. But the FR is a real spanner in the works.

So here's the pros and cons.

925:
- Cheaper scope
- Default f/10 view and AP not as good.
- Cheap FR
- f/6.3 with FR should be similar to Edge (it does flattening and correction)
- f/2 with HyperStar should be the same as Edge

925 Edge:
- More expensive.
- Default f/10 view and AP better than 925.
- Expensive FR with possible issues

The Edge also has a few other little features like vents and a 2" diagonal, but I was planning to get the 2" Celestron eyepiece kit (because I own none now and it seems like a good way to start) which comes with a back for the 925 anyway.

On the other hand I would hate to buy the 925 and then feel I wish I had gotten the Edge version later... lots of people do post about regretting not getting Edge versions but very few of them focus on the focal reducer part. I don't have a list of favourite things that I want to look at or image in order to determine what focal lengths are important to me and how important a focal reducer is in the grand scheme of things. All I read is either "f/10 is too slow and difficult for AP" and "f/2 is too wide and makes everything look too small". So my assumption is that f/6.3 is some mythical sweet spot.

Any comments?

[Rod771 (Rod)]

Just bite the bullet and get the C11 Edge HD. Then you will have everything you seem to desire, F10 , F2 with Hyperstar , F7 with .7x HD reducer and.... a nice wide aperture scope for visual.

Go on you know you want too.

Or If visual's not a big deal, the C8 Edge HD is cheaper again and offers all the above options. Having said that, I've still seen great views through an eight inch scope too.

Good luck

[dannat (Daniel)]

the c11 is too heavy to startvwith, the c8 edge is a good suggestion
By all reports the edge/act range of act are better Ota for photography-less problems with outer stars

I still think a 8" Newtonian is a good start much shorter focal length , means you can lessen exp times. Long focal length imaging is demanding of user & mount

[Camelopardalis (Dunk)]

+1 what Rod said

The Edge scopes are great for visual - they have the flat(ter) field and coma free edges. Then there are the vents...I've fitted mine with the TEMPest fans for quicker cool down. And they have mirror locks, that you'd appreciate once you start imaging...focus once, lock up and slew away.

As for the size, it depends on what camera you intend to use. The C8 is smaller, with a narrower baffle tube than its brethren so only really suits a smaller chip (read: APS-C), whereas the 9 and up have a wider baffle tube that can feed larger sensors.

There's no magic with f/6.3... I was "imaging" (I've only just started, so bear with me!) with my C8 Edge the other night with the Celestron 0.7x reducer (US$299) and on a couple of targets I felt like I should take the reducer out and image at f/10 I didn't in the end, sacrificed resolution for brightness instead.

When it comes to hyperstar...the lenses are expensive. You could get a nice little refractor (used) for about the same money, and it'd probably be lighter. Whether it would be as well corrected is another question though.

[Poita (Peter)]

The quality varies a lot more with the standard 925, the edge scopes seem pretty consistent, so get a star test if considering the 925.

[Camelopardalis (Dunk)]

Originally Posted by dannat

I still think a 8" Newtonian is a good start much shorter focal length , means you can lessen exp times. Long focal length imaging is demanding of user & mount

+1 too... if I didn't already have the scope I have for visual, an 8" f/4 newt makes a lot of sense, saves $$$ too.

[Rod771 (Rod)]

Originally Posted by dannat

the c11 is too heavy to startvwith,

Yes, you would need to look into a bigger mount than the CGEM if you were serious about imaging with the C11 HD but its only 3kg heavier than the 925 HD