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Why is it such a common problem now days for binoculars to have too much eye relief r (1 Viewer)

wdc said:
Jerry, I'm wondering if you could post a photo of your workaround. If it means someone can see the whole FOV WITH glasses on in an EII, I'd like to learn how.

Thanks.

Bill
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Bill,

As I look closely at this it appears that I’ve just managed to turn down the eyecups. But, I had to take them off first before they could be rolled into position then remounted on the eyepieces.

Best,
Jerry
 

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Troubador said:
I know what you mean but consider this.

Many eyecups work like an old draw-pull telescope don't they? I mean one tube fits inside another and just like you make the telescope longer by pulling one tube out from inside the other with eyecups this happens when you scew it or pull it out.
It seems as easy as falling off a log to make a longer tube possible by making both tubes a bit longer. But hang on, our eyecup needs to close down far enough to allow spectacle wearers to use it. So we can't just lengthen and lengthen the eyecup. We could do what the telescope makers do and make our telescoping eyecup out of 3 tubes. This would allow us to close it all the way down but still get a longer length when extended. Right?
No. Because to make 3 tubes fit inside each other means the eyecup needs to have a bigger diameter and at narrower interpupillary distances the fat eyecups won't fit around some fat noses so your binos will only accommodate a narrower IPD range.
And the bino maker might have already made the eyepieces as fat as he dare giving us both a decent eye relief and a great field of view. And which is sexier on the specs: a wide fov or telescoping eyecups?

I really can't see an easy solution here that will satisfy both spectacle wearers and non -specs wearers and all the variations in facial contours and spectacle lenses and frames.

Lee
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Lee,

While Renze de Vries and I were researching the evolution of the Swift 804 Audubon, one thing that stood out to me was the enormous engineering efforts undertaken to get the eyecups right. In the end they settled on rubber eyecups not too different from the Nikon E and SE models.

For eyeglass users, one curious aspect that remains largely unrecognized is that the eyeglass prescription itself makes an important difference. Other factors held constant, myopes can usually get along with less eye relief than presbyopes. Optically it can be shown that they also experience a somewhat greater field of view and lower magnification. For this reason, among eyeglass users there will probably never be a universal solution.

Ed
 
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Thinking about this for a bit, it seems to je there is a pretty simple, at least partial, solution. There are numerous binoculars with screw off eye cup assemblies. Many, myself included, have used this to our advantage when we need more extension. Just unscrew the eye cup and insert an 0-ring, replace the eye cup and there is an extension equal to the thickness of the 0-ring. The problem here is finding an 0-ring of just the right dimension. If the thickness is proper for the desired extension, then there is a chance the 0-ring won't let something screw down properly because the outer diameter is too large.

The solution lies in the fact there has to be a myriad of small, precision metal bushings. I happened to luck into finding a few of a 1 mm thickness that looked to be made to order for placing over the threaded eye cup assembly. On went a couple of bushings, the screw on eye cup assemblies fit back properly, everything screwed in and out and fit properly, and unless you did it yourself, you would never know anything had been extended.

The answer lies in finding a source for these bushings or in convincing manufacturers to keep some on hand. Problem is there are bound to be some variation in the size of some binocular in that this won't work.
 
Steve C said:
Thinking about this for a bit, it seems to je there is a pretty simple, at least partial, solution. There are numerous binoculars with screw off eye cup assemblies. Many, myself included, have used this to our advantage when we need more extension. Just unscrew the eye cup and insert an 0-ring, replace the eye cup and there is an extension equal to the thickness of the 0-ring. The problem here is finding an 0-ring of just the right dimension. If the thickness is proper for the desired extension, then there is a chance the 0-ring won't let something screw down properly because the outer diameter is too large.

...
Click to expand...

So, yeah. In my case a rubber faucet washer adds just the right distance from the eye lens on my Swaro SLC-HD (about 3 mm). If I use different glasses the 0-rings may be removed. I think they look great either way!

Ed :t:
 

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elkcub said:
Lee,

While Renze de Vries and I were researching the evolution of the Swift 804 Audubon, one thing that stood out to me was the enormous engineering efforts undertaken to get the eyecups right. In the end they settled on rubber eyecups not too different from the Nikon E and SE models.

For eyeglass users, one curious aspect that remains largely unrecognized is the that the eyeglass prescription itself makes an important difference. Other factors held constant, myopes can usually get along with less eye relief than presbyopes. Optically it can be shown that they also experience a somewhat greater field of view and lower magnification. For this reason, among eyeglass users there will probably never be a universal solution.

Ed
Click to expand...

Ed
Thanks for this which explains why, when I became slightly less myopic, I needed to extend my eyecups a little from the fully screwed down position.

And my local plumber's suppliers keeps a nice selection of o-rings in stock.

Lee
 
When I started out with O rings, I bought a mixed bag from the bay.

I am in the UK and if you search for simplybearings.co.uk you will be able to choose sizes. Not cheap but a helpful company.
 
The-Wanderer said:
When I started out with O rings, I bought a mixed bag from the bay.

I am in the UK and if you search for simplybearings.co.uk you will be able to choose sizes. Not cheap but a helpful company.
Click to expand...

Excellent information Wanderer, thanks for posting.

And if you plan to use o-rings that would need stretching to a larger diameter to fit on your binos then you should choose EPDM, Viton or Neoprene/Chloroprene as these will resist cracking due to ozone attack much better than plain old nitrile.

Lee
 
I don't wear eyeglasses, but do eyeglass wearers really ever need extended eyepieces on their binoculars? Why not just offer two sets of eyepieces. One stationary low eyepiece (that should be good and cheap for the beancounters) and then another extendable one for those who don't wear glasses.
 
justabirdwatcher said:
I don't wear eyeglasses, but do eyeglass wearers really ever need extended eyepieces on their binoculars? Why not just offer two sets of eyepieces. One stationary low eyepiece (that should be good and cheap for the beancounters) and then another extendable one for those who don't wear glasses.
Click to expand...

Yes, there are some who wear large frame glasses who almost never extend the eyecups, and there are those who use frames that fit closer to the face that may need to extend the eyecup a setting or two.

I agree with the two eyecup solution if it's too difficult to design an eyecup that both maximizes eye relief for eyeglass wearers and gives more than enough eyecup extension like Canon 10x42 IS users have reported.
 
Simply bearings also sell O rings by linear measure and diameter, plus a glue: I have never tried it but if the glue is good that might be a better way of doing it if you are more nimble in the DIY department than I am now.
 
JerryLogan said:
Bill,

As I look closely at this it appears that I’ve just managed to turn down the eyecups. But, I had to take them off first before they could be rolled into position then remounted on the eyepieces.

Best,
Jerry
Click to expand...

Thanks Jerry for posting the picture and the explanation.

-Bill
 
On my recently acquired (second hand) Bushnell, the eye cups extended only a meager 9mm above the lens. Buying used old bins does have the advantage that you don't need to be very careful with them. So, I took apart the eye-cup, which consisted of an aluminium cylinder that moves up and down via a slot system and this cylinder in turn is covered by a fairly solid rubber cylinder, which was simply glued over the aluminium part. i could easily loosen it with a toothpick, move the rubber piece a couple mm upwards and then glue it back. Quite happy with the end result, since I can still use the original rainguard.


The orange arrow shows the gap caused by increased height, the white/ grey arrow shows the aluminium ring on the inside.
 

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Justabirdatcher

I agree with Lee.

One of the problems with fold down eye cups for specs wearers is often that fully folded back eye relief is too short and the lowest intermediate position gives not enough.
 
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Synaps said:
On my recently acquired (second hand) Bushnell, the eye cups extended only a meager 9mm above the lens. Buying used old bins does have the advantage that you don't need to be very careful with them. So, I took apart the eye-cup, which consisted of an aluminium cylinder that moves up and down via a slot system and this cylinder in turn is covered by a fairly solid rubber cylinder, which was simply glued over the aluminium part. i could easily loosen it with a toothpick, move the rubber piece a couple mm upwards and then glue it back. Quite happy with the end result, since I can still use the original rainguard.


The orange arrow shows the gap caused by increased height, the white/ grey arrow shows the aluminium ring on the inside.
Click to expand...
Good solution! Nice pictures! It is great to give other members some ideas how to deal with binoculars that have too short eye cups.
 
Synaps said:
On my recently acquired (second hand) Bushnell, the eye cups extended only a meager 9mm above the lens. Buying used old bins does have the advantage that you don't need to be very careful with them. So, I took apart the eye-cup, which consisted of an aluminium cylinder that moves up and down via a slot system and this cylinder in turn is covered by a fairly solid rubber cylinder, which was simply glued over the aluminium part. i could easily loosen it with a toothpick, move the rubber piece a couple mm upwards and then glue it back. Quite happy with the end result, since I can still use the original rainguard.


The orange arrow shows the gap caused by increased height, the white/ grey arrow shows the aluminium ring on the inside.
Click to expand...

A great and neat solution. When doing anything like this it is very important to ensure both eyecups are at the same height. This is common sense anyway and it looks like you got this spot-on. But if you don't get it right you end up not looking down the optical axis and this can mean you see more chromatic aberration and maybe other stuff that impairs the image.

Lee
 
Thanks, Lee and Dennis.

When doing anything like this it is very important to ensure both eyecups are at the same height....
Click to expand...

Yup, quite important and properly taken care of.
Though I am not very precise in reading and typing answers, I tend to be extremely precise when tinkering ;)
 
"When doing anything like this it is very important to ensure both eyecups are at the same height."

Unless your eye sockets are uneven then you must take that into account.;)
 
[email protected] said:
"When doing anything like this it is very important to ensure both eyecups are at the same height."

Unless your eye sockets are uneven then you must take that into account.;)
Click to expand...

LOL. An excellent point Dennis. This can be checked for by watching out for a row of 3 birds on a wire. Look at the one in the centre and lift up your binos. If you now find you are looking at the bird to the right or the one on the left, then you have this problem. Just joking :-O

Lee
 
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