Posted by Les on December 17, 2000 at 14:30:33:
In Reply to: GG alignment posted by Larry Thompson on December 17, 2000 at 12:24:07:
YOur friend is half right. The fresnel lens does have a focal lenght, but has no bearing on sharness, except for the amount it displaces the ground glass.
I measured mine (a Crown too) and it mic'ed 0.070". Find a shim that thick, place it between the GG and the lens and it should work just fine.