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widening eye-cups (1 Viewer)

lmans66

Out Birding....
Supporter
United States
Has anyone found a way to widen rubber eye-cups. I have seen lots of information on eye-relief but little on actually widening the eye cup itself. Given that everyone has different sizes of eye-sockets, it would stand to reason that binocular companies would recognize that and provide some widening over-lay... Ideas ?
 

eitanaltman

Well-known member
That’s something I’ve thought about too. Certain bins like the Meostar 32, Swaro CL, Sightron SII 32 and clones have narrow eyecups that don’t work great for me.
 

wllmspd

Well-known member
Cheapest option is to buy some of the biggest bike Inner tubes and the make your own, use contact adhesive to customise the fit. I have a whole set for a wide range of different eyepieces I have for binoculars and telescopes. Very cheap solution, you get exactly what you want! I did write a forum post somewhere on doing this.

Peter
 

Stephen Prower

Well-known member
Peter

Re: Widening binocular eye cups using bicycle inner tubes*

It is expensive to buy new bicycle inner tubes solely in order to cut them up to use for bulking out binocular eyecups.

I have built up a collection of inner tubes of different diameters and thicknesses from the gash bin of my local cycle shop. I cut them in the shop so that there is no question of my 'winning' a free tube by repairing them.

In this way I can avoid the use of glue by bulking out the eye cups to my chosen width with several sections of tube of increasing diameter.

The eyecups of my Opticron 8x32 SR.GA, for instance, are bulked out with six thicknesses of tube (three doubled over sections) to my preferred diameter of 40mm.

Another source of inner tubes is my own used inner tubes. But since I patch them usually at least five times before giving up on them, they are a limited resource. I pick up a few tubes in sizes I don't use that have been jettisoned as litter by the side of the road by riders after they have had a puncture.

The main problem for me is obtaining inner tubes for tyres of over 32mm or 2.125in section, especially superfat mountain bike tyres. They only appear rarely in the gash bin of the local shop. I suspect that the reason is riders moving over to tubeless tyres.


Stephen


* Reconstructing eyecups is a different job. But I add while writing that I have done it successfully a couple of times. I prefer it if the result doesn't look like a dog's dinner. But function is of course for field use the name of the game
 

eitanaltman

Well-known member
Peter and Stephen - a picture is worth a thousand words here! I’m having trouble visualizing what you are describing. :)

My biggest confusion is how to get the round over at the top of the eyecup? Slipping something over the outside barrel is straightforward but then you’ve got this rubber cylinder poking up into your eye socket like old school bins. I don’t want to lose the comfort of the smoothly rounded contact point between eyecup and eye socket.
 

Stephen Prower

Well-known member
Imans66

As you'll have seen, I attached a photo of my modded Opticron 8x32 SR.GA to illustrate my reply to your other thread, re diopter adjusters, today.

I attach the photo for convenience also to the present thread to show the 40mm wide eyepieces of the Opticron*.

I have a suspicion that I needed an inner tube of a size to fit a 40mm, or somewhere round about that, tyre for a least the outer doubled over section of the three sections that I used.

Peter alluded to the point.

The largest common sizes of inner tube are tubes to fit a 32mm or 2.125in tyre.

But I also, like Peter, have found that, for the larger common widths of binocular eyecup, tubes to fit a 32mm or 2.125in tyre may not be wide enough.

If it helps you therefore to know what types of bike use wide tyres, and so wide inner tubes, it is principally shopper bikes, and some touring bikes that may use over 32mm tyres, or fat-tyred mountain bikes that may use over 2.125in tyres.


Stephen


* It is no coincidence that the photo makes the Opticron look llike a mini-version of an old 7x35 Extra Wide Angle binocular. To get a good quality image encompassing the full field of view of the Opticron, just like a 7x35 Extra Wide that I own, I have to turn down the eyecups. Then to reproduce the good fit to the face of the 7x35 Extra Wide, I have to bulk out the eyecups
 

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Stephen Prower

Well-known member
Eitanaltman

Our posts crossed!

The answer to your question is: Use doubled over inner tube for the outer section, namely the section that makes first contact with your eye socket.

You'll see the result in a photo of my Opticron 8x32 SR.GA that I've now attached to a post in the present thread.

In another binocular, I might use doubled over tube for the inner sections, or not. If not, I would simply recess them a little to avoid contact with the eye socket.


Stephen
 

Stephen Prower

Well-known member
Eitanaltman

Here's a better photo!

On this occasion the fold-down eyecups of the Opticron were in the up position, and I was adding a bit of extension.

It was before I discovered that the best view for me through the binocular, even though I don't wear spectacles for viewing, was achieved with the eyecups folded down*.

So under all the gubbins the eyecups are in the up position.

To complete matters, I'd like to send a naked photo of the Opticron, but I am afraid I have not got one.


Stephen
 

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jring

Well-known member
Hi,

thank you very much for the good images and explanation - unfortunately (from a regular biker's perspective) my stash of defective inner tubes is well filled...

Joachim
 

lmans66

Out Birding....
Supporter
United States
You just have to wrap around once ....just the width of diameter and height go the cup, right?
 

yarrellii

Well-known member
Supporter
Stephen, Peter, this is of the greatest interest for me. Thank you so much for taking the time to explain it in detail.

I couldn't agree more with eitanaltman, the whole program of lovely binoculars simply gets jeopardized (when not directly ruined) by narrow eyecups. If it wasn't for the eyecups, I'd likely be using a CL.

Also, my problem with the 8x30 E2 eyecups is not width, but actually the fact that, just like Stephen with the SR.GA I seem to get a wider view with eyecups down (even though I don't use spectacles), but this makes for a pretty uncomfortable and annoying position, so I've been looking for a way to gain a bit of height (with the eyecups all the way down). Incidentally the eyecups of my SE do allow for a "semi-rolled down" position, I don't know if this is because the rubber is softer/thinner/older than the E2, but I don't seem to be able to replicate this with the E2. See attached picture of the SE eyecup. It is rolled down in both cases, but you can create an intermediate position, as you can see.

I ride on 700x35 mm tyres, so old spares should provide with great fun tomorrow. I'll keep you posted! Thanks again.
 

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Stephen Prower

Well-known member
Imans66


I understand you want simply to bulk out the eyecups.

Here are step by step instructions for ordinary eyecups -- Constant diameter, no lumps and bumps:

You select a length of inner tube with a diameter that looks to fit the eyecups with just a little bit of stretch to hold it gripping tight.

For each eyecup, you cut a section measuring just over twice the height of the eyecup. You don't cut twice the exact height because when material turns back on itself, the turn consumes a little bit of length. Also you may want the doubled over edge to protrude a little to offer you greater comfort.

You sleeve the section over the eyecup.

You turn the upper half of the section which protrudes above the eyecup back over the lower half. You will have to stretch the upper section. Be careful not to damage the binocular when doing so.

If a single doubled over section does not bulk out the eyecup sufficiently, you add sections. They can be single thickness sections, or doubled over sections.

However, since single thickness sections have a 'hard' edge, it is better not to use them for the outermost section. Instead use them, slightly recessed, only for the inner sections.

Say if I have misunderstood you!

The language of 'sections' and 'diameters' can be confusing.

Cyclists talk of 32mm section tyres, rather than 32mm diameter tyres. It could be because 32mm is a width measurement. Inner tubes in turn are not specified by diameter, but by the section of tyre they are intended to fit. But should you come to cut up an inner tube, then you cut it by length also as a matter of terminology into 'sections'.


Stephen
 

Stephen Prower

Well-known member
Yarrelli

Good to hear from you!

Be careful! Without knowing the thickness of the rubber of your inner tubes, I suspect tubes for 35mm section tyres will require to be stretched too far. The ideal is that you stretch inner tube simply enough to make it grip. Otherwise you risk paying an unacceptable price in damage or distortion*.

If you intend to sleeve inner tube over turned down eyecups in order to achieve a small amount of extension, look at the second picture of the Opticron. From the outside:
* There is a doubled over section of tube
* There is a second doubled over section of tube. The thickened 'roll' of the second section supports the thickened roll of the first section
* There is the turned up eyecup of the Opticron.

Your situation is different. The Nikon's eyecups will be turned down. You won't want as much extension.

But the set up may give you some useful ideas.


Stephen


* 'Dog's dinner' distortion, or more serious distortion
 

yarrellii

Well-known member
Supporter
Stephen, thank you so much for the tips. I understand what you mean. I'll follow your suggestion and try to look for something a bit thicker. I normally use tyres that are far from their stretch limit, so that they are less prone to punctures. For example, right now I'm using some Schwalbe that are meant to be used from 28 to 45 mm wide tyres, and I'm using 35 mm. But I might be better of with some inner tube for mountain bike tyres.

Yes, in my case I really miss the intermediate steps that twist-up eyecups usually provide. For example, in the FL series I quite often use the one-but-last stop, which allows me to see the entire FOV. Same with the E2, with the eyecups all the way up, I'm far from being able to enjoy the entire FOV. With the eyecups rolled down, I get a stunning ultrawide view, but it is so uncomfortable that I hardly use it (sometimes for stargazing or stationary landscape observation when I'm completely still). So an intermediate position would be a great bonus.
Thanks again!
 

wllmspd

Well-known member
Tyre labelling is a load of hurt, I bought what I thiugh I would fit but failed. So I bought one super ultra huge fat-bike tube and slice bits off as I need. You can then cut it so you have a long strip, then you can use contact adhesive to tune the exact diameter you want. I tried stretching, but the unstretched bit tends to construct the eye lens width. I prefer a light friction fit as sometimes I need to adjust the inter-eye correction or I am using individual focus binoculars and So I want to be able to rotate the cup about. I played about with wing design and some scissors... once I had one I like I just trace round it for other eyepieces. I have custom ones for a range of binoculars and other eyepieces... all for the cost of one fat bike tyre and a tube of glue. The roll down design is helpful if you want to use glasses and get closer.

Peter
 

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lmans66

Out Birding....
Supporter
United States
Imans66


I understand you want simply to bulk out the eyecups.

Here are step by step instructions for ordinary eyecups -- Constant diameter, no lumps and bumps:

You select a length of inner tube with a diameter that looks to fit the eyecups with just a little bit of stretch to hold it gripping tight.

For each eyecup, you cut a section measuring just over twice the height of the eyecup. You don't cut twice the exact height because when material turns back on itself, the turn consumes a little bit of length. Also you may want the doubled over edge to protrude a little to offer you greater comfort.

You sleeve the section over the eyecup.

You turn the upper half of the section which protrudes above the eyecup back over the lower half. You will have to stretch the upper section. Be careful not to damage the binocular when doing so.

If a single doubled over section does not bulk out the eyecup sufficiently, you add sections. They can be single thickness sections, or doubled over sections.

However, since single thickness sections have a 'hard' edge, it is better not to use them for the outermost section. Instead use them, slightly recessed, only for the inner sections.

Say if I have misunderstood you!

The language of 'sections' and 'diameters' can be confusing.

Cyclists talk of 32mm section tyres, rather than 32mm diameter tyres. It could be because 32mm is a width measurement. Inner tubes in turn are not specified by diameter, but by the section of tyre they are intended to fit. But should you come to cut up an inner tube, then you cut it by length also as a matter of terminology into 'sections'.


Stephen

Sounds like an easy fix...thanks. I will play with as it doesn't appear difficult. Reminds of the early digiscoping days where we would experiment with just about anything. It does boggle my that manufactures haven't thought of eyecup wideners or extensions as an accessory ...
 

Stephen Prower

Well-known member
Peter

I've shared your experience. Especially the faff about bicycle tyre and inner tube sizing.

I went the way of compiling a selection of old inner tubes, and then choosing which one to use for a job by eye, because I had access to old tubes.

Your advice to go with one tube, and buy one that is very large (ie large as indicated by the size of tyre that the inner tube is labelled to fit) is, I agree, the way for most people to go.

My largest tube is a tube for a fat mountain bike tyre. The tube is marked as supplied for a 26x2.3/3.0 tyre (mountain bike tyre sizes being customarily measured in inches). The minimum section of 2.3in may be fat, but the maximum of 3.0in is obese!

The tube is a precious asset. A dealer friend brought it back to me from the shop that he manages. His commuting distance by bicycle is some 20 miles. Understandably he only brought me a two foot length!

My memory is that the size of tube is good for cutting wings to fit a 40mm diameter eyecup.

I emphasise that I give the size as a guide only to the minimum size for a tube to buy to use to bulk out eyecubs etc by your method.

A bicycle dealer should be able to be more specific.


Stephen
 

Stephen Prower

Well-known member
Yarrelli

The problem of using a section of tube that is stretched beyond a certain limit to create an extension is that it will contract back inwards once it is unsupported.

I attach photos of a 'rescue' Optolyth 8x40 Alpin. A previous owner had, as well as botching a reassembly, cut off the eyecups. I would describe the result of my re-creation of the eyecups as a cosmetic dog's dinner.

[Nevertheless, functionally, a success story: the re-created eyecups did do the job perfectly well!]

For small extensions though, as in the case of the extension I made to the eyecups of the Opticron (See photo attached to Post #8), the contraction may sometimes be exploitable to do a cosmetically tidy job.

I would experiment with a tube to fit a 28/45mm tyre before dismissing it as too narrow for the job, say, of creating an extension to a 40mm eyecup.

However there is less reason to bother about stretching the tube when merely seeking to freeze adjustable eyecups in an intermediate position.

I attach a photo of the job that I did to freeze the eyecups on the notorious cheapo (£33 new when I bought) Celestron '8x30' Nature*.

Indeed you will see that, in this instance, I fully exploited the tendency of inner tube to contract when stretched.


Stephen


* Apart from rattly eyecups that sometimes didn't hold up, the badges tended to fall off - and as measured by Henry Link, the Celestron was actually a 6.8x27! Optically though it was very good, so an excellent lightweight field binocular.
 

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wllmspd

Well-known member
I even tried to predict the useful diameter fit from the mm/inch spec numbers and the ones I bought that I couldn’t use… grr! The one I ended up with was a Schwalbe Inner Tube SV13J Fatbike (Presta) 26 x 3.5-4.8" that I got for £10, more than others but economical as I’ve got plenty left. (Not that the valve type is important ;-)!


I have daytime, night time binoculars and a series of astro eyepiece pairs, so a wide range of diameters to fit, the largest are 56mm diameter. The thinness of the tyre material helps stop the eyepieces getting too fat and clashing with your nose.

Happy innovating!

Peter
 

Stephen Prower

Well-known member
Sounds like an easy fix...thanks. I will play with as it doesn't appear difficult. Reminds of the early digiscoping days where we would experiment with just about anything. It does boggle my that manufactures haven't thought of eyecup wideners or extensions as an accessory ...

I'm glad I helped.

WJC reminds us that the importers etc are in the business of sourcing binoculars, not dispensing worldly love.

I would suppose one can expand that to: 'The business of sourcing high value items like binoculars', the problem of small value items like accessories being that they take just as much trouble to source and import, for much smaller reward.

The small man does not fill the gap because he/she cannot discount the cost of getting his product to market against a sufficiently high price that is also acceptable to the consumer.

Or some such!

I encountered the problem in the field of cameras.

The Chinese manufacturers churn out cheap red dot sights in thousands for hunters, paint-ballers, etc, but when I bought mine there was just one small man right round the world, and one factory making the mounts to fit them to a camera hot shoe.

Later the small man circulated that he had had to lower the specification of the mount because rising costs meant that he could no longer make a profit on sales of the present model.


Stephen
 

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