To: atm{at}shore.net
From: MLThiebaux 
Reply-To: MLThiebaux 


Richard Schwartz wrote (Mon, 31 Mar 2003 14:04:13 -0800):
>
>... If the diagonal is very close to the focal plane, perhaps error in the
diagonal surface can't do much damage....
>

Richard, you're right.  Earlier I posted an argument based on geometric
optics showing that the effective wavefront error due to a slightly
spherical secondary varies as the square of its distance to the focal
plane.

Martial Thiebaux
Rawdon Hills, Nova Scotia

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