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    Re: SNO-T "night" sight tube?
    From: Alexandre Eremenko
    Date: 2018 Nov 23, 01:11 +0000

    Dear Brad,
    Thanks for the video.
    
    You wrote:
    
    > I am unsure as to what utility, if any, anti-reflective lenses would have in 
    celestial navigation.  AR coatings attenuate the light transmitted through 
    the lens. 
    
    Apparently this is not so: AR coating INCREASES the amount of light passing 
    through the lens, not attenuate it.
    See, for example:
    
    https://en.wikipedia.org/wiki/Anti-reflective_coating
    
    First I was a bit confused with terminology, but when I found the Russian 
    translation of AR, I realized that this is
    very familiar to me. The Russian term is more suggestive "????????????? ??????" which literally means
    "enlightened optics". It allows MORE light to pass by surpressing reflection.
    
    The reason to use it in astronomical instruments is exactly the same as the 
    reason for its use in binoculars.
    It must be especially important in the night (Galileo) scopes.
    
    Alex.
     
    
    

       
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