On Sun, 29 Feb 2004 18:11:03 GMT, Chris L Peterson
wrote:

Why don't you use a diagonal? It is a complete myth that you should collimate
without one. If you use a straight through EP, you are in fact moving the mirror
spacing out of its optimal position and introducing slightly more aberration.

If your diagonal is not exactly collimated you can't collimate the
SCTcorrectly. Changing the mirror spacing should not change the
collimation, only the amount of spherical aberration.