Eye Relief
 

So I am wondering why the eye relief for a Leupold vx-2 4-12 is listed as Low: 4.90, High: 3.70. Then for instance, Nightforce NXS 3.5-15 is listed as a straight up 3.9. Is there something different that makes the eye relief constant for the Nightforce? I know I am comparing 2 scopes on different levels but there must be something different.

I don't have any NF scopes....

But there has to be a range...........why NF does not state what the range is, is their business but having and advertising a larger range would be good for business in my mind.
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These days most quality scopes have near constant eye relief. There is no valid reason not to have near constant eye relief.

Bingo. If a scope requires you to move your head to a different spot depending on if you are min or max magnification, get a different scope, and pick one that has a quality build. What kind of circus games are you playing while trying to shoot. consistency = accuracy.

^^^^ yes

but I'd rather have a range of 3.7 - 4.9 over a constant 3.9. A constant 4.5 would be a winner.

there are lots of different scopes out there and maybe you'll find one that has eye relief that long. the problem is that most traditional scope mounting locations dont allow the rings to be that far back, so the popular eye relief falls around 3.5 to 4 for many scopes

I would take a constant 3.9" any day. 3.9" is plenty , and it won't be hard to mount on most rifles.