--- David Dunn <david.dunn@albertsons.com> wrote:
Good page. It makes me wish that I could start now. Luckily I wont have to hog mine out as deep since I want to go with an f/10. One question I have is why do you use a flat for the optical secondary instead of a parabolic 8" mirror?
If the secondary is anything but flat, it will alter the primary f/#. Also, a flat is infinitely easier to figure than just about any convex surface. A concave secondary means a Gregorian configuration, which tends to be much longer than a Cass, and even most Newts. If you really want to go unobstructed, check out the Sasian design- of course it means you must figure a toroidal secondary (royal pain in the butt). All in all, a "folded" Newt is a marvel of optical simplicity. C. __________________________________________________ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com