Re: [ATM] homemade diagonal

[Ken Hunter <atm_ken_hunter@yahoo.com>]

Hi Jerry...

If you are seeing bending of the lines when you touch
the glass, the glass is bending with the touch. It
should not take any great amount of pressure to make
the lines move about on the glass. A slight touch here
and a slight touch there will (SHOULD) align the lines
for you and get the glass so that the narrow part of
the wedge is closest to you which is the usual way of
testing the flats.

Yes, you can definitely test the telescope with
un-aluminized optics but be aware that you will get
about 4% of 4% light through to the focal plane. It
makes for very dim images.

Those "clamshell dings around the edge" will effect
the image more than you suggest. ALL OF THE SECONDARY
MIRROR contributes light to ALL OF THE IMAGE except
the portion of the image that is vignetted. You should
make sure the dings are not reflective because the
altered wavefront from that part of the secondary will
be scattered over a large area of the image.

Ken Hunter

--- "Jerry B. Hillman" <JBHillman@ev1.net> wrote:

> The down side is the edge has a couple of clamshell
> chips that extend into
> the flat by about .125". Since the flat is larger
> than necessary by about
> .15" minor axis, and since the mate to this flat is
> scratched right in the
> center, plus I am out of dental plaster, I am going
> to use this. If I black
> out the chips after it is coated I don't think I
> will see a problem.
> Basically, all I should see is a less than perfect
> edge on the FOV.
> Clear skies, Jerry
> 



	
		
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