RE: [ATM] Another Astigmatism question, but at the sphere stage

["Jerry" <wa4guu@verizon.net>]

Like seeing planetary detail through a telescope is to some degree a learned
skill that one can practice and get better, so is seeing the detail in a
Foucault test. 

James focograms are pretty good and are worthy images to practice seeing the
detail in the surface.

What do you see?

For example, Optic C Axis 1 Horizontal Robo Foucault Images page one is
enough for the sake of discussion. You have looked at all of the images.  

How could you tell that dark artifact is not on the glass? It is not dark on
one side and light on the other. If it is in the surface it is a material
difference not a shape difference.

Can you see and explain how that hex shape came about that is apparent
particularly in the zone 1 and 2 pics? 

Do you see that the crater rim shows in every image?

Do you see the triangular texture of intersecting tracks across the mirror?
Since I see this on other focograms I wonder if this is real or the nature
of pixels on a monitor. But I have seen milder on real tests. Maybe the
monitor enhances this. If it is real it is something to do with a multiple
of three. Either in stroke ration or stepping around the barrel.

And the three way texture probably has something to do with the radial
streaking that one can reason is not thermal but on the glass. It is part of
the roughness. 

Am I imagining here?

Maybe.......

I am going to hit the sack tonight so you have time to post the pic Dale. It
will be fun.

Wish all threatened by the storm well

Good night.


Jerry




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