Daniel wrote:
When I say "generous" that may be an understatement. . . . . It also means that focus can be achieved at any distance behind the primary all the way to infinity, . . .
Thanks, so there is no theoretical limit. Chuck wrote:
The reason for a short-coupled camera is usually lack of swing-through room on a fork mount.
So the backfocus limit is a physical interference constraint. Thanks for the heads up on that one. I would not want to break a focuser tube off! Daniel wrote:
The drawback is the slow focal ratio which grows with the backfocus.
Although the light-weight easy-to-handle SCT package size is a big plus, one of the more confusing things to me about buying an SCT is their owners shell out for a scope with a 3000mm focal length and then immediately turn-around and spend another $200 for an adapter to turn it back into an 1100mm f/l Newt. I'll try to physically measure the backfocus and report back. Now if I can just find my ruler marked "infinitiy", "generous", "doesn't fit", "right-on", "adequate", "too small" and millimeters. -:) - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net