From: "Mel Bartels" 
To: 
Reply-To: "Mel Bartels" 


>>>
I don't think any manufactures of telescopes "figure" using star
test. If they did and I was buying one of their telescopes I would have to
test it on the bench first. I would not trust star test figured optics.
<<<

But the same reasoning extended would lead one to not trust any optics then
because judgements are always made as to when the optic 'is good enough'.
If it is not the star test then it's the numbers of a Foucault test or
interpretation of interferogram.

The star test is uniquely qualified to pass final judgement.  I've relied
on it for many years and it has pointed out subtle errors that I missed,
yet could see upon return to the testing stand.  It is difficult to figure
from and not for the uninitiated.  In addition, very few really know how to
interpret star tests.  For instance, they focus their attention way too
much on edge and spherical aberration issues and never learn how to see
zones and roughness.

Mel Bartels

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