The S&B 4-16x56 Polar is more than likely the best low light scope made. I wish I could give you a hands on review but it is well out of my price range.
European hunters hunt well into the night, so European scope makers design scopes that cater to that type of hunting. High Quality glass and coatings plus large objectives make their scopes some of the best in the world for low light conditions. I'd look at some of the offerings from S&B, Zeiss, Meopta and IOR designed for low light hunting.
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