|
An "imagining optimised" scope just has the primary mirror set a little closer to the focuser than it woukd be set for a "visual" scope. The focal length, in particular the focal ratio, us more significant photographically, where exposure times are shorter in a fast scope.
For visual use, and a very fast Newtonian will show more coma - a phenomenon thst only affects reflectors. Coma is a result of the eyepiece not being able to focus the light at the edge of the field of view, and is seen as the stars having little comet tails radiating out from the center. It isn't a defect, and can be corrected for by using a coma corrector. A coma corrector is essential for photography, but for visual it is upto the individual. I have an f/4 8" Newtonian and I don't use a coma corrector as I just don't find it objectionable. I actually found the one I used killed light transmission -THAT I found more objectionable. Yet other people swear by them...
Either way, an imaging optimised scope can still be used for visual. It just means needing yo use an extension tube to allow the eyepiece to focus.
|