Lawrence Sayre wrote:

On Thu, 04 Mar 2004 04:13:37 +0000, Richard F.L.R. Snashall
wrote:



Lawrence Sayre wrote:

What size, quality, and specific type of lens would be required to
use a Foucault tester as a Ross Null Tester for a 30" ~f/4
mirror? Does anyone make such a beast?


You may find there are multiple answers to this question. For
example (if you
have OSLO available to you):

http://users.rcn.com/rflrs/Ross_Test.len


Lawrence Sayre




Sorry, but I'm exclusively a Linux OS person. Can't run most Windows
stuff.


R t G
2153.491 444.5243
1635.134 11 BK7
-1635.134 992.8908
inf 3.175
-1625.6 -3.175 MIRROR
... return path matches ...


The size of the lens is about half the size of the mirror
(in this case, the mirror was 8" and the lens was 100 mm).


Lawrence Sayre


--

Rick S.

http://users.rcn.com/rflrs