Re: [APML] Strange star image

[Herm <hermperez@worldnet.att.net>]

Nice sharp focus!.. anyways this is probably caused by the bevel in the
mirror.. mask out the outer 1/8" of the mirror and it will go away.
Collimation issues will show up on the corners of the frame with elongated
stars, usually. I refine collimation every time I set up, a small tweak of
the secondary will make it perfect.. the primary never needs adjustment.

I masked my mirror by carefully applying flexible black electrical tape..
if you use a good brand such as 3M then it will not leave any residue if
you ever take it off. Only 1/8" of the mirror needs to be masked, the rest
of the tape is bent and stuck to the side of the mirror.. its a 5 minute
job even if you are a clutz.

Why is the flare asymmetrical?, is anything protruding into the light
path?.. such as the focuser or a barlow etc.. 

a.roerig@t-online.de (Andreas Rörig)  wrote:

>please take a look at this test image I took yesterday with my new 8"
>f/4 Newton Vixen R200SS:
>
>http://home.t-online.de/home/a.roerig/test/r200ss_test_01_aus.jpg
>
>What could cause the flare of the star (Capella) to the left side? Could
>it be that the mirror is to tight within his mirror cell? Collimation
>should be ok. Any ideas?

Herm
Astropics http://home.att.net/~hermperez


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