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Eye Relief

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#1 LarryinCA

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Posted 05 December 2003 - 09:11 PM

I am currently using some very old Agfa 10x40 binos, but can't wear my glasses with them. If I were to upgrade, what is the minium eye relief for eyeglass wearers?

Larry

#2 Rusty

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Posted 05 December 2003 - 09:49 PM

It tends to be personal, and of course there's advertised eye relief vs. actual.

There's one other thing to consider if you've been doing cyclopian viewing. I found I could get by with 15mm because I was "cheating", pushing my one eyeglass lens against the EP eyecup, and pushing my glasses closer to my eye on that side. Ya' can't do that with binocs.

Personally, I can tolerate 17mm, but 20mm is better. :bigshock:

#3 EdZ

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Posted 06 December 2003 - 03:07 PM

In 3 out of 4 binocs the actual eye relief is about 3-4mm less than advertised. I wear glasses all the time with binocs. I can get away with 13mm to 15mm and see the entire field stop. That would be binoculars that might be advertised around 16 to 18mm eye relief.

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#4 brocknroller

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Posted 06 December 2003 - 06:10 PM

Larry,

Your facial features and the thickness of you eyeglasses also enter the equation when considering binocular eye relief. A lot of Japanese and Chinese binoculars are made for flat Asian faces. I have a high-bridged nose and deep set eyes (look somewhat like Sam Elliot, I'm told -- wish I had his money so I could buy a 15X60 Zeiss Classic!). I find that I need at least 17-18mm to see the entire FOV with most binoculars, and I have thin polycarbonate glasses. Even 17mm may not be sufficient if the lenses are deeply recessed like the Swift Audubon (advertised as 17mm, actually about 12mm for eyeglass wearers). Then take that 12mm and minus the thickness of your glasses and the distance of your eyes behind the glasses, and you might end up with about 9mm ER and a very tiny FOV. Edz has posted some actual ER figures for various binoculars in his articles on Cloudy Nights. Dana Brunner also gives some actual figures in her (his?) reviews of 8X and 10X binoculars. Todd Gross, another eyeglass wearer, comments on actual eye relief in his binocular reviews at www.weatherman.com

If the actual ER of the binoculars you're considering is not listed in those sources, call the manufacturer and ask a technician for the actual figure. Although not many binoculars boast generous ER of 20mm-23mm, if you do buy one (e.g., 10X50 Orion Ultraview, 8X42 Swift Ultralite), chances are good that the ER will be sufficient unless your glasses look like the bottom of coke bottles. The alternative is wearing contact lenses. There are newer ones available that can compensate for mild astigmatism. Not sure how well they work.

Brock

#5 brocknroller

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Posted 06 December 2003 - 09:47 PM

ADDENDUM:

Unlike most dealers, Astronomics lists the "useable eye relief" on the binoculars it sells instead of the manufacturer's advertised specs. It has the correct distances for the Swift 8.5X44 820 Audubon (12mm), the 8X42 Ultralite (18mm), and the 10X50 Kestrel (10mm) so the rest are probably reliable.

http://www.astronomi...s.asp?n1=6&t1=2

Brock

#6 LarryinCA

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Posted 06 December 2003 - 09:49 PM

Thanks for the input. The two I've been considering are Orion Ultraview 10x50 and Pentax 10x50 PCF WP. Looks like plenty of ER with Orion but haven't seen any figures for the Pentax.

Larry

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Posted 08 December 2003 - 01:54 PM

The Orion Ultraview should be fine with glasses. I have two sets (one with old fold down eyecups, newer one with push down eyecups) and they have plenty of eye relief (around 20mm usable) for me with fairly thick glasses. Note with the Orions I would inspect in person if possible before buying, my experience is that they vary in quality control. Both of my Ultraviews, though collimated L-R, have one side slightly off collimation so that the sharpest part of the field is not centered (note I bought both used). The 10x50 Ultraviews have a curved focal plane and noticeable off axis astigmatism but are wider field than the Pentax. I have only briefly seen the Pentax PCF in a shop but I believe they also have a similarly generous eye relief (~20mm) but a smaller field (~50 vs 65deg). Good luck.

#8 brocknroller

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Posted 11 December 2003 - 12:24 AM

ADDENDUM 2:

Here are Dana Bunner's 8X and 10X bin reviews:
www-personal.umich.edu/~bbowman/birds/al_brushaber/binocs.html

Brock


#9 edcannon

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Posted 11 December 2003 - 10:21 PM

I find online that Pentax 10x50 PCF WP eye relief is 20 mm. Include "eye relief" in Google search. They have a narrow actual field of view, only 5 degrees.

Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA


#10 brocknroller

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Posted 24 December 2003 - 01:29 PM

While short eye relief is a concern for eyeglass wearers, too much eye relief can also be a problem for some people.

In this review comparing the Swift 8.5X44 Audubon with the Nikon 8X32 Superior E (SE), the reviewer mentions the "blackout" problem with the SEs because of the high eye relief (17.4mm):
http://www.talkabout...ges/161863.html

Todd Gross also remarked about this in his review of the SE series. The small exit pupil (4mm) is also a factor -- I had a similar problem with my Nikon 10X35 E2 (3.5mm exit pupil) and it has only 13.8mm ER. The smaller the exit pupil, the more critical the eye position to avoid blackouts.

From corresponding with other SE owners, some see the blackout problem, others do not. I experience blackouts in the right EP of my 8X32 SE when not positioning my eyes correctly (since I also saw this only in the right EP of the Nikon 10X35 E2, it must be partly due to my eyes).

By not pressing my eyes deeply into the eyecups and adjusting the IPD with changes in distance (narrowing the IPD for close focus), I'm able to avoid blackouts while using the 8X32 SE. Unlike the above reviewer, I don't experience this problem when viewing with my eyeglasses.

As an eyeglass and sunglass wearer, I'd rather have too much ER than not enough since I can always pull back a little and adjust the IPD to avoid blackouts and see most if not all the FOV. But these techniques might not work for everyone or be too bothersome.

Brock

#11 KennyJ

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Posted 24 December 2003 - 02:54 PM

Hello again Brock and Merry Xmas !

Although I've "officially signed off " already for the Xmas break, even at this late hour on Xmas Eve I could not resist re -checking the latest posts to this favourite forum of mine .

At least one aspect of your latest commentary I feel is worthy of highlighting and bringing to the attention of other binocular users.

It is a thing I have tried to explain myself in previous corespondence , but alas without any apparant success or feedback , probably because I have failed to explain the potential problem as clearly as what you have !

It is the matter of finding oneself having to "fine -tune"
the right diopter relative to real -life distance of viewed objects.

Almost every "How To Use " type of binocular articles I have ever read would appear to include instructions that lead the unassuming new binocular user to presume that once the right diopter and left ( central ) focusser have been adjusted to suit any individual's eye conditions when looking any given object at the chosen set distance ,then a "simple tweaking" of the central focusser thereafter will automatically "re-focus to perfection" any objects viewed that happen to be at real -life distances far removed from that at which the original "personal setting" was adjusted.

"Fine tuning" of this kind is probably an aspect of binocular usage that more experienced users take for granted and carry out almost " subconsciously" without thought to mention when attempting to summarise the performance of any given glass.

As such I think this is just another example of the kind of fine detail that a commentator such as Brock deserves great credit for.

In reality -- out there in the field -- there is indeed a "perfect" distance of eye -relief for every individual person , with every different kind of binocular, which can vary slightly for objects at different distances , both for eye-glass wearers and for those less fortunate.

This is why the "screw -out" / "click -stop" type of right diopter adjuster found on all modern "top -end" Roof Prism binos is so widely praised as being a vast improvement upon fold -backable rubber eyecups , such as are to be found on my favourite Zeiss 7 x 42 Roofs and Nikon SE series Porros.

Indeed ,eye -relief on the Zeiss is probably TOO generous for some users , but as Brock states , "TOO much ER " is at least manageable by the experienced user.

"TOO LITTLE ER " however, as found with my 15 x 70 Little Giants for example , is a problem that cannot be rectified.

In spite of the obvious advantages of modern "incrementally adjustable" eyecups,I still much prefer the softness of the venerable rubber type , and especially when these are of the "winged" variety to cut out stray light.

Obviously , with "winged eyecups" , such fine adjustability based around concentric twisting actions can never be achieved, but with rack and pinion type focussers it could.

Once again -- Season's Greetings to all -- Kenny .





#12 brocknroller

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Posted 25 December 2003 - 01:06 AM

Merry X-mas Kenny and other CN binocular enthusiasts.

Yes, I do need to adjust the right diopter for different distances on all my binoculars. The single exception was the Fujinon 6X30 FMTR-SX, which focused from 20ft. to infinity and had amazing depth of field.

However, what I was referring to above was that in order to avoid blackouts with the SE and E2, I have to adjust the interpupillary distance (IPD) of the eyepieces so that my eyes stay dead center from close focus to infinity.

In between wrapping presents (I wish I had gotten Santa's helpers to do this, I'm a lousy wrapper), I was thinking more about the blackouts and why it's only a problem with my right eye. Later, I noticed that my right eye is set farther away from my nose than my left eye, and it's also set farther back in my face. No, I don't look like a freak, it's too subtle to notice without careful study (and measurement), but it's significant enough to make a difference when the bin specs are critical, as with the combo of high eye relief and small exit pupil.

Then I tested myself for my "dominant" eye. You can do this by holding a pencil at arm's length and lining it up with an object across the room. Close one eye and then the other, and the eye that lines up with the object is the one you use to line up objects with your binocular. My dominant eye is my left eye. Since my right eye is "off center," this explains the blackout problem. I line up a bird or celestial object with my left eye and center that eye in the left EP while my right eye is slightly off center in the right EP because of my asymmetrical facial features. I wouldn't be surprised if this is also the reason why some SE owners experience blackouts and other do not.

When bins are designed, there is some consideration given for individual facial features (IPD adjustment) and eye prescriptions (ER and R diopter adjustment) and hand size (housing size and campfering). But even those specs are tuned to range of the average person. Some people will need larger or smaller IPD, or more diopter adjustment, or more or less ER, or a larger or smaller gripping area.

Ideally, the best binocular would be one that was custom designed for your face and your eyes and your hands. If Bill Gates were a binocular enthusiast, I'm sure his would be. :-) But for the rest of us, we have to learn to adjust to the binocular. Sometimes I can adjust, like the SE, and other times, I cannot adjust, like the Swift Audubon.

Getting back to your issue of diopter adjustment -- although this feature is mainly there to adjust for differing eye prescriptions, the depth of field of the bin also affects how often and how much you need to adjust the diopter setting. One negative I forgot to mention about the Nikon 10X35 E2 is its shallow depth of field. I'm forever fiddling with the diopter setting after I adjust center focus. The E2 focuses down to 10 ft (though it's advertised as 16.4 ft. -- a rare instance when a company underestimates rather than exaggerates a useful bin spec). When focusing close, the depth of field isn't very good so I need to continually adjust as birds move around the feeding area. With the SE, I don't have to do this unless there is movement of a couple feet. With the E2, it's a matter of inches.

Depth of field -- yet another factor to consider when choosing bins (at least for terrestrial use). Binoculars are probably the most "personal" of optics (telescopes, cameras, etc.) because you have to use two eyes, two hands, and your face. Everything has to line up just right for a comfortable, relaxing, enjoyable experience.

Oh, oh. Just heard some noise up on the roof. Better get to bed. :-)

Brock


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