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  #21  
Old 04-22-2015, 04:21 PM
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astroboof astroboof is offline
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Hi Norm, well, failing a scientific or not test you could just try to do as much viewing as you can in as good a weather as possible and find out what you can, but even better is to look through other reflectors in the same aperture region and also ask other experienced astrograzers their impressions through the ep of your XT10G.

Or, for coatings alone, you or someone else could grab a good torch and shine it up the coight of your primary whilst observing the effect it has from the open end of your scope, hopefully the light that comes through is minimal and very, very even.
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  #22  
Old 04-22-2015, 07:14 PM
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Vinnie Vinnie is offline
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Norm mirrors made by Synta these days are pretty darn good. (ie Orion/Skywatcher and others)

I was going to say don't shine a torch from behind the mirror as that might put you off, but sure if you do, don't be concerned if light gets through. As long as it doesn't light up like a search light.

Also don't freak out over a dirty mirror. It has to get really dirty before you'll have problems.
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  #23  
Old 04-22-2015, 07:21 PM
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Vinnie Vinnie is offline
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Norm read this article, and get to the bit with the image of the moon shot with a P&S Camera and an bare glass "Mirror" ie a piece of glass that is ground but still clear glass

http://www.hbastro.net/halloran-scope.htm
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Incurable Refractorholic. EQ6 GoTo, GP2 and EQ3 mounts. EPs: 2.5 & 4mm Vixen NLV. 5, 8, 13, 17 & 22mm Vixen LVW. 30 & 40mm Vixen NPL.


"If a straight line is the shortest distance between two points, a circle is the longest distance between the same point provided the circle is big enough" - Sellar and Yeatman
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  #24  
Old 04-22-2015, 10:16 PM
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Norm Stevens Norm Stevens is offline
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thanks guys! once again very useful advice!
Thats is an interesting read Vin! I have actually be thinking about in the future building a scope.
I'm not anywhere near ready to take that on, but 5 or so years from now who knows. but i would want to build a much bigger one.
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