Re: [ATM] first ronchi images,,,, ouch

["Mel Bartels" <mbartels@bbastrodesigns.com>]

> that gave advise on that subject).  So I decided to put it on the ronchi
> and
> take a few photos,,,, well here is the link,  please try to be kind.  I do
> want feed back though as I believe I have a turned down edge, and maybe
> more....  any advise you can give is allways gratefull.
> 
> I believe I need shorter, 1/6th? strokes, COC MOT to correct this, a
> slight
> "W" possible


You have some parabolization or correction occurring in the outer 20% of the
mirror surface. That's OK.  If you can manage to not change the edge with
respect to the rest of the mirror while you add parabolization to the rest
of the mirror, you actually don't have to fix anything.

I do not recommend short strokes that cross the center.  That will actually
worsen your situation, by driving the remaining correction into a narrower
edge zone.  You could try 1/3 strokes with large side swing which will tend
to flatten the edge and drive correction into the middle portion of the
mirror.

Mel Bartels


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