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Old Thursday 24th August 2017, 23:19   #1
Apochromat
ZEISS VICTORY SF 8x42 KOWA 883 Prominar 25x-60x Wide

 
Join Date: Aug 2017
Location: Germany
Posts: 10
Star Test Tool

Hello to all,
I have a question: Star tests are able to display residual spherical aberration, astigmatism and coma within a bino/ scope. How do you normally use a star test for evaluating the quality of your bin´s/ spotting scopes?
Would such a tool be useful for anybody?

Would somebody want a tool with tiny artificial star test structures illuminated by a homogeneous backlight LED (white/ blue, green, red LED) for in- house/ home use as well (in a darkened room)?

Any suggestions welcome, as I have contacted a very reputable maker of such star test structures. They are willed to make such a tool at a reasonable price, but asked for any suggestions.

I would politely ask for any input. As a result that company would start to make such a tool.
If this would be a wish, I could just make the contact between You and that company.
Thanks
Michael

Last edited by Apochromat : Friday 25th August 2017 at 05:33.
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Old Friday 25th August 2017, 15:27   #2
Binastro
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Join Date: Aug 2012
Location: S.England
Posts: 3,286
One can buy pinholes or double pinholes backlit artificial stars ready made.

Or one can use a fine needle in say tinfoil or aluminium foil to make small apertures. I think some use a wood board or cork behind to make a clean hole. One can probably find on the internet how to make clean holes.

My telescope maker used these lit from behind at about 15m distant for star tests.

I think maybe a lens system is used for infinity testing.

I just use stars such as Polaris that doesn't move.

Or small ball bearings in the day to use the Sun as an artificial star, maybe 15m away. One can use two close together for double stars. Glitter stars.
I use 6mm or so ball bearings which I carry in my pocket for instant binocular tests.
Some people use distant electrical tower balls about 4 inch diameter or decorative balls at a distance.
Or raindrops hanging on leaves after a rain shower.
I also use house lights visible 2km away.

Last edited by Binastro : Friday 25th August 2017 at 15:48.
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