Re: ATM Ronchi offset

[Mel Bartels <mbartels@efn.org>]

> chosen to use Ronchi testing. I obtained a program
> online and have been playing around with it. My
> question is about the "offset", how do I make sure I
> start in the right place?  Moving the mirror forward


Easiest for me is to pick a ronchigram image and adjust the testing stand
until it best matches.  Now roll forward/backwards through the images
using the adjustment on the test stand and compare them to what they ought
to be.  If you reach the proper curve too early for instance, then the
mirror is overcorrected.  You can narrow this down to specific zones of
the mirror.

Mel Bartels