I did this sort of thing when I made my 8"f/5 many years ago, along with the custom made focuser that held the camera only fractions of an inch above the tube. That was for photography, and as I remember, I was shooting for 100% illumination over a 1.3" circle so that the edge falloff would be minimal at the corners. It worked, as I have lots of slides/negs that show very little falloff.
My current 10" is intended for visual only, and I don`t plan on any exotic wide field eyepieces for the immediate future, so my 1.95" diagonal provides 100% for a reasonable fov. I just found the number of baffles the CAD program called for a little "amusing". If I were really concerned that I had a problem in that area I would go the flocked paper route also, but again was shocked at how expensive that stuff has gotten. I guess I`ve become an curmudgeon (sp?)!!

• Find the source. - crockett - April 20, 2000 - 19:26 UTC