Monday, March 18, 2013

Is exit pupil related to eye relief?

I just need some clarification on eye relief and exit pupil.

It sounds like most binoculars today are made with ample eye relief so that most binoculars will work for people who wear glasses or don’t. However, in one description I read, it mentioned that having too much eye relief is a bad thing.

I did a quick little experiment with my Leopold rifle scope (which has an eye relief around 4”). When holding my eye about 4” from the scope everything is bright and I can see the full image in the scope. If I move my eye further away, the viewing area seems to shrink (vignetting as I have seen it described). When I move my eye closer than 4”, I cannot see the object very clearly either; the viewing area seems to move around and either get smaller or split.

Thanks for your help.



Thanks for your questions, Nick.

Too much eye relief is seldom a problem in a binocular. On a binocular, the function of the eyecup is to adjust for each individual user. Since you sometimes wear glasses, you'd be looking for a binocular with a minimum of 15mm. of eye relief. 

 Normally an eyeglass wearer would not need to twist the eyecups up--your glasses provide the distance needed for the correct focal point. Higher quality binoculars have multi-position eyecups to accommodate different peoples' needs.
Exit pupil is not related to eye relief.  Exit pupil, or, the dot of light you see coming though the binocular-- is the same size when your eye is at the eyepiece as it is when the binocular is held at arm's length.

Hope this helps. We can certainly chat at (800) 289-1132 if you have further questions.


Eagle Optics

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