Re: [ATM] Pinhole size article in ATM 3

["Francis J. O'Reilly" <foreilly@verizon.net>]

Olivier,

This is probably very much on topic.

Some use a pinhole with their testers, some do  not. I do when I'm using my 
own tester. If I'm at a workshop, I use what is there.

Setup is harder with the pinhole. The foucault test is by it's nature 
somewhat subjective, lately, I'm more interested in null testing for a 
parabola, it's less quantitative, but I don't care. I'm more interested with 
what can be seen at the eyepiece when the mirror is done. ONe of my next 
projects, a very soon next project will be to make a large flat with a hole 
in the center to use in my autocollimator.

Francis 

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