Hi Evan
best thing you can do is download
ccdcalc.exe, run it and input differing cameras, scopes and deep space or solar system targets. This program will give you a visual idea on how well different cameras/scope combinations work. You just select you scope, desired camera (and focal extender or reducer) and target, and it will give you an image typical of what you can expect...and info image scale, FOV etc.
Its all about image scale and FOV of a sensor with a given particular scope.
ccdcalc will give you that info. So download it and have a play. Oh I think there are some other object/target packages that can be download and input to the ccdcal database of objects. Sorry I cannot remember where they are on the webz but they are out there.
Brendan
edit:
meh...took an extra 2 mins...
here are the additional image packages for ccdcalc.