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Usable eye relief in binoculars (1 Viewer)

Canip

Well-known member
I just finished measuring usable eye relief on virtually all of the binoculars in my collection.

See https://binocular.ch/the-pinac-collection/#collection ,
then click on any binocular in the collection that you are interested in, to find the eye relief / usable eye relief data in the individual posts.

This covers roughly 250+ binoculars and may be useful information for some of you.

Just to sum up again what this is about:

"Eye relief" is usually mentioned in binocular specs by the manufacturer and measured from the surface of the so-called "eyelens" (the outermost lens of the eyepiece), but most often, such information is of limited use since eyecup designs most frequently don't allow you to place your glasses directly against the eyelens.

"Usable eye relief" is measured from the rim of the eyecup (folded down or screwed fully in) and is most often more relevant for eyeglass wearers.

Two caveats regarding the information I provide on my website:

I have tried to measure carefully, but measuring usable eye relief is sometimes not as straightforward as you might think ("uneven" design of eyecups, etc.), so the stated measured values may perhaps be up to 0.5mm beside the correct value. So "12 mm" in fact means anything between 11.5 mm and 12.5 mm.

Plus, e.g. "15 mm" on one bino does not necessarily mean the same thing on another bino, because different shapes, forms and sizes of eyecups will allow you to get closer or less close to the eyepiece with your glasses.

Feedback welcome.
Canip
 
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Thanks, Canip, very useful info especially for people who use their binos with glasses; for people who don't use glasses the diam of the eyecups, the shape of their rubber rims and the way the eyecups fit into their eye sockets are also quite important factors.
 
Thanks, Canip, very useful info especially for people who use their binos with glasses; for people who don't use glasses the diam of the eyecups, the shape of their rubber rims and the way the eyecups fit into their eye sockets are also quite important factors.

There are a lot of things to consider, apart from the things you and Canip have mentioned, like most people's faces not being symetrical - this impacts glasses wearers and non glasses wearers alike. The different sizes, shapes and curves of glasses further complicate things.

Then of course there are features of the optical design - such as the degree of spherical aberration, and randpupille which influence the margin of error of the Eye Relief.

Good stuff Canip :t:






Chosun :gh:
 
Fantastic resource, chapeau!

I also noticed the APM 6x30 porro that you saw in pre-release guise. A metal bodied compact 6x porro is really appealing indeed! I'll be keen to see a copy when they're available. I'm increasingly dissatisfied with my 6,5x32 Kowa BDII, I just don't get on with it really well - not as relaxed or pleasing a view, in the long run, as I had hoped.

Cheers!
 
Canip, this is a super resource! :)

I do have a query, though, on one of your measurements. The Ultravid HD Plus 7x42 you have listed as having a measured/usable eye relief of just 14mm. Is this really correct?

I query it because, as a glasses wearer, I have concluded that I need a minimum of 16mm of usable eye relief, with an ideal of 17mm. Roger Vine measured the eye relief of the Ultravid HD 7x42 (not the 'Plus' version) as being 17mm, which is exactly what Leica specify. I thought the only difference between the HD and HD Plus was the optics, with the chassis/casing unchanged...?

If your measurement is correct, I am now extremely confused, having tried (and fallen head over heels in love with) the Ultravid HD Plus 7x42.
 
Canip, this is a super resource! :)

I do have a query, though, on one of your measurements. The Ultravid HD Plus 7x42 you have listed as having a measured/usable eye relief of just 14mm. Is this really correct?

I query it because, as a glasses wearer, I have concluded that I need a minimum of 16mm of usable eye relief, with an ideal of 17mm. Roger Vine measured the eye relief of the Ultravid HD 7x42 (not the 'Plus' version) as being 17mm, which is exactly what Leica specify. I thought the only difference between the HD and HD Plus was the optics, with the chassis/casing unchanged...?

If your measurement is correct, I am now extremely confused, having tried (and fallen head over heels in love with) the Ultravid HD Plus 7x42.

Just measured again, I stand by my number of 14mm, and I think it's perfectly explicable.
As you can see, the surface of the eyelens, from which the 17mm according to Leica are measured, is quite a bit recessed into the eyecup, so measuring from the rim of the eyecup gets you easily several millimeters less actual - or better "usable" - eye relief (compared to the "technical" eye relief acc. to the specs. which I find less relevant in practice).

Canip
 

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Just measured again, I stand by my number of 14mm, and I think it's perfectly explicable.
As you can see, the surface of the eyelens, from which the 17mm according to Leica are measured, is quite a bit recessed into the eyecup, so measuring from the rim of the eyecup gets you easily several millimeters less actual - or better "usable" - eye relief (compared to the "technical" eye relief acc. to the specs. which I find less relevant in practice).

Canip
Terrific, thank you very much for double checking, and so quickly(!), Canip. :)

I am now properly confused, and wondering why I found it so easy to position these binoculars and observe the full field of view without any issues whatsoever. I have tested so many different pairs of binoculars over the past 7 or 8 months, and I'm not aware of any others with so little eye relief which have not caused me considerable difficulties, or been even remotely comfortable, in use. These are the most comfortable, and to my eyes, optically the most delightful/wonderful (not sure I can define exactly what I mean by that), pair of binoculars I have ever looked through.
 
The shape of the eye glasses frame , even the thickness of the lenses can influence usable eye relief. I don't think there is a international standard on how to measure eye relief in sport optics. Pat (thank you canip for taking the time to take all those measurements and your rating on the respective binos- used your info many times!)
 
The shape of the eye glasses frame , even the thickness of the lenses can influence usable eye relief. I don't think there is a international standard on how to measure eye relief in sport optics. Pat (thank you canip for taking the time to take all those measurements and your rating on the respective binos- used your info many times!)
Thanks, Pat.

Yes, the variation in the shape/size/thickness of the frames of the two pairs of glasses I wear regularly is what led me to reject so many instruments at lower price levels. My newer frames, which have a very slightly weaker prescription (yes, my eyesight is actually improving with age! ) are the ones proving most difficult to use with binoculars. My older pair are still regularly used because they are less susceptible to fogging up when wearing a mask (due to Covid rules), so bins need to work with both pairs. I've had to reject some wonderful mid-priced binoculars which would have done the job more than adequately, because of the nature of my glasses frames. I know, cheaper to get a new pair of glasses! ;)

Incidentally, I was actually looking for a 10x and the instrument I finally settled on was a Noctivid 10x42. I was initially trying to find a 10x32 which would work well for me, but failed in that quest (positioning with small exit pupil being the main culprit, I suspect). The Noctivid was the best fit, although I could have happily opted for the Conquest HD, which was almost as comfortable, if optically not quite so luxurious.

I was originally planning to purchase just one pair of binoculars, my cheap and cheerful 8x42 Bushnell instrument does a remarkably good job (considering how little I paid for it many years ago). But, I really do like the idea of having something a little more compact and lighter as well, and was exploring/testing 8x32's when I happened upon the 7x42 Ultravid HD Plus.

This has all come about because, since the beginning of the pandemic, I have started using binoculars very much more than I had for many years. I have access to some very fine 'classic/vintage' optics (some of my own and some belonging to other family members), but none of them have enough eye relief for me, now that I wear glasses full time.
 
So is eye relief measured when eyecups are fully out or in? I presume 'out' as measurements like 16mm only make sense then. But equally how is that a useful measurement for glasses wearers who use binoculars with eyecups down? Would like to understand as I don't wear glasses yet for birding.
 
...These are the most comfortable, and to my eyes, optically the most delightful/wonderful (not sure I can define exactly what I mean by that), pair of binoculars I have ever looked through.

Frankly, once you've found that it suits you, who cares what the stated (or indeed) actual eye relief is? ...
 
So is eye relief measured when eyecups are fully out or in? I presume 'out' as measurements like 16mm only make sense then. But equally how is that a useful measurement for glasses wearers who use binoculars with eyecups down? Would like to understand as I don't wear glasses yet for birding.
No. Eye relief has nothing to do with eyecups. See Canip's Post 1. It is an optical concept and measured from the top lens of the eyepieces to the place where the exit pupil allows you to see the full field of view without blackouts. Of course when you come to use the binos, eyecups are very much involved hence Canip's efforts to provide 'usable eye relief' data.

Lee
 
So is eye relief measured when eyecups are fully out or in? I presume 'out' as measurements like 16mm only make sense then. But equally how is that a useful measurement for glasses wearers who use binoculars with eyecups down? Would like to understand as I don't wear glasses yet for birding.
Eye relief is simply the distance between the ocular lens and your eyes. For glasses wearers, the instrument cannot be held as close to the eyes because the glasses form a barrier. A glasses wearer using binoculars with insufficient eye relief will only see the centre of the image, the edges will be cropped and blacked out.
 
No. Eye relief has nothing to do with eyecups. See Canip's Post 1. It is an optical concept and measured from the top lens of the eyepieces to the place where the exit pupil allows you to see the full field of view without blackouts. Of course when you come to use the binos, eyecups are very much involved hence Canip's efforts to provide 'usable eye relief' data.

Lee
Beat me to it, Lee, with a far better explanation! 😁
 
Frankly, once you've found that it suits you, who cares what the stated (or indeed) actual eye relief is? ...
Yes, that's very fair comment, Patudo. 🙂

Fact is, I am trying to understand why the UV's fit me like a glove, when no other bins I've tried with similar eye relief have been even remotely close to fitting me, or offering me the full field of view.

I'm also wondering what 'gems' I may have dismissed without trying.

Anyway, I'm just a little confused...😉
 
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