Quote:
Originally Posted by Peter Ward
 seems trivial, I know, but you could actually see the difference from top to lower edges. |
Oh I totally agree. Theoretical tolerances are extremely tight. In practice it's hard to get (and stay) there. I have no doubt about the quality of field improvement. I've 'nailed it' a handful of occasion by luck but would be incapable of reproducing it. I remember reading in the book "Celestron - the early days" a paragraph written by Ceravolo when he was working there saying he got an SCT to 1/20th of a wave on a rig by centering the corrector on a test rig. Then went on saying "of course, 4 cork shims aren't going to keep you there".