Quote:
Originally Posted by Wavytone
Dunk using a compressor on a C8 for visual use is a bit pointless... the central baffle and aperture in the back of the mirror cell restrict the maximum field of view to about 1.3 degrees. You might as well use a big eyepiece - an ultra-wide 40-50mm will show everything there is to be had in the vignetted field of view just as well as a tele compressor combined with a somewhat shorter eyepiece, and it will do it very well, whereas the compressor and a short eyepiece could easily end up being not so sharp.
To get MORE sky you need a shorter refractor like the ones you identified and it is for precisely the same reason I have a 102mm f/7 ED refractor, which fills a big 2" eyepiece giving a maximum field of view around 3.8 degrees which the C8 cannot come close to, no matter what you do to it.
I'll also add that with a similar setup (the refractor + my 180mm f/15 Maksutov) the refractor has become just a very big finderscope and to be honest i don't use it nearly as much as I expected; if there's a choice the Mak always goes on the mount but not always the refractor. FWIW you're welcome to try my refractor anytime...
However an 8" f/5 dob is a very different beastie and more likely to be useful especially if the optics are excellent. On and off over the past 2 years I have contemplated a larger dob, but refrained because I simply don't get out often enough to justify it.
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Thanks, I'd love a peek
I usually use my 40mm with the C8 and last time was getting kicks from using it with the C11 + reducer, still only about 1.3-1.4 degrees, but the views of the Orion Nebula didn't disappoint.
But thinking about it even 8" f/5 is still a lot of focal length...8" f/3 would be much more appealing
I guess I was wondering if I was fundamentally missing something...just chasing that unicorn with the scope on it's back.
For those long winter nights, a bigger Dob has gone through my mind more than once...