Light gathering comparison?

[Erik Kiser]

Buddy of mine currently shoots a Leupold 6.5-20 and isn't crazy about the low light performance of it. He's getting ready to build his son a 300 Ultra and asked me about scopes. I've read a lot of good stuff about the Sightron S3 and was wondering how it compares in low light to a Leupold, NF, or other top scopes. Thanks

 

[murf]

I just got a Trijicon 2.5-10 X 56 and love it gathers plenty of light but it's only half the power of what your friend has now. He needs to look at exit pupil size as that is basically what determines an optics light gathering capability (I am sure glass quality and coatings have a little to do with it also).

 

[lloydsmale]

problem isnt the scope its the power range of the scope. to get any kind of good light gathering with a 20x scope youd need at least a 80mm objective lense.

 

[bruce_ventura]

I agree with both responses. How old is your friends Leupold? Modern lens coatings are very good. Most scopes above the $500 price point have similar transmission (85-92%) in low light. A few percent difference in transmission isn't noticeable.

What is the objective size? If it's 40 mm, then he will have the best low light performance at magnifications below about 7X, depending on his age. If it's 50 mm then he can increase the magnification a bit more to about 8X.

 

[Erik Kiser]

I believe it's a 50. Scope is probably 6 years old or so. It's a Leupold LR with the parallax adjustment on the side. Sounds like its just the nature of the beast. Thanks guys for the responses