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Re: Binocular Recommendation?



When I measure the distance from my eye to the front of my glasses, I
get approximately 20 mm. Therefore, if I use my glasses and binoculars
with less than 20 mm eye relief I will not see the whole field. I
suspect this is fairly typical, but some people will have a mm or two
more or less than this.

I suspect few eyeglass wearers will see the whole field with 11-mm
eye-relief binoculars. Most eye-glass wearers will see most of the
field with 19-mm eye relief.

Also note that the eye-relief is measured to the lens, not to the rubber
cup. So eyeglass wearers want to buy binoculars that have a rubber cup
that can be turned down so the binocular eyepiece lenses can be held
real close to the glasses. Most modern high-quality binoculars are this
way, but I have seen some where the rim around the eyepiece is rigid and
separates the eye and eyepiece by an additional 2-4 mm.

Also note that the biggest reason to leave your glasses on (aside from
convenience) is if you have bad astigmatism. If you are simply
nearsighted or far sighted, just take your glasses off and refocus.
Usually the right eyepiece is adjustable to accommodate eyes that need
different correction. I need something like minus-3 in my left eye and
minus-5 in my right. So I can take my glasses off, set the right
eyepiece to minus-2, and then use the central focus control.
Unfortunately I also have fairly bad astigmatism. I often have a
difficult time deciding if I see better through binoculars with my
glasses on or off. If my astigmatism were not so bad, I would probably
always take my glasses off.

Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton College
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu


What sort of minimum eye relief is required for viewing with your
glasses on? I checked the site, would 19mm probably be OK? What about
11mm? (I'm guessing *not*)

Joel R.