• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Binocular tactics??? (1 Viewer)

Pinewood said:
A member of this forum suggested to me that myopics should have fewer problems with eye relief, becaue our specs make things seem smaller, and we get a bigger field. Certainly, I see a bigger FOV with my glasses on, and the cups down, then with my glasses off, and the cups up.

Happy bird watching,
Arthur :scribe:
Click to expand...

And that minification (making things smaller) is what contributes to KB blackout problems in some bins with a lot of myopic correction ... the effective ER becomes increased because the negative corrective eyeglass lens diverges the light moving the effective position of the exit pupil back (so the eye is effectively "too close").

Hyperopes who have a positive eyeglass correction would suffer less from blackout problems with the SE and more from lack of ER.

So stronger myopes should be happier with shorter ER than weaker myopes or all hyperopes (and the stronger a hyperope you are the more you need long ER). Not all eyeglass wearers are the same.

I see this effect with my Yosemite 6x30 too. Just in the more corrected right eye. A little bit of eyecup twist up (a couple of mm) gets rid of it i.e. I move the eye further away from the EP and the KB blackout disappear.

The other issue you describe, seeing the full field, is nothing to do with myopia and everything to do with insufficient ER or too much distance from the eyeglasses to the eye as I mention above. Hyperopes and even normal vision people wearing sunglasses have this same problem (again depending on the fit of the glasses).

The usual myope's problem viewing through their bins without eyeglasses is having enough focus "beyond infinity" to get the negative correction they require. For some bins there isn't enough. It's often speced and needs to be more than your prescription (including astigmatism correction).

And if you have astimgatism then not using your glasses with bins isn't a good option.

I can see the difference in view with my -1D (left) and -3D (right) of astigmatism between wearing and not wearing my glasses with a bin (assuming I can deal with the spherical -3D in both eyes with the bins) with any halfway decent bins. So for me not wearing glasses is not really an option anymore.
 
Kevin Purcell said:
But people fit eyeglasses in all sorts of ways with vertex distances below 10mm (though your eyelashes might start to hit the lens) out to 30mm (big eyeglasses worn down the nose often by old guys!). These difference distances make all the difference.

QUOTE]

Thanks for the very informative post, Kevin, and also for saying far more succinctly what I was trying to get at; and for explaining how to measure real er. "Vertex Distance" is what I meant when I said er of eyeglasses....and yes, one tiny problem is that my eyelashes do brush off the lenses....John Lennon glasses, Sophia Loren eyelashes!;) (And Cyrano de Bergerac nose....)
Click to expand...
 
Last edited:
Strong myope! I guess that describes me. When I don't use glasses, which is rare because of astigmatism, I twist the dioptre setting way over, as I need -7.5

Happy birdwatching,
Arthur
 
Pinewood said:
Strong myope! I guess that describes me. When I don't use glasses, which is rare because of astigmatism, I twist the dioptre setting way over, as I need -7.5

Happy birdwatching,
Arthur
Click to expand...

So that's more of an indication of the difference in correction between the eyes than the total amount of correction (the bin can do that).

But -7.5D difference is a lot!

You are not the oddball who is a hyperope in one eye and a myope in the other? With a prescription of something like +4D in one eye and -3.5D in the other eye are you?

I'm myopic but only a 1.5D difference between the eyes (when I include astigmatism ... otherwise they're about the same for spherical).

You had problems with the SE blackouts too didn't you? I think I can see why. In just one eye?

What is your prescription?
 
Kevin and Arthur,
This is a very interesting discussion to me as I haven't been able to correlate some minor black out issues with certain bins. For example the SE (though maybe the 8x32 not the 10x42), bins seem to be known as a black-out prone bins, while I haven't read much about 8x42 Ultravids being problematic in that area. I have 10x42 SEs with no black out issues while my Ultravids are finicky.

I am mildly far sighted, + 1.75 right eye, +1.5 left eye, with no astigmitism. I feel I have slightly deep set eyes, but I don't know how to measure this. I typically use my bins without glasses. Is there anything you can tell me about my eyes and a propensity for black outs? For example would I be testing my luck by buying a 8x32 SE, sight unseen? I forgot, I also have a very narrow IPD, my bins are usually very close to the narrowest setting.

Thanks,
John
 
Pinewood said:
Kevin,

Sorry, I was writing of IF binoculars, not the right dioptre with a CF binocular. Both of my eyes are -7.5.
Click to expand...

Yeap, that's a pretty big prescription. And would explain the allergy to the SE's.

So strong myopes need not apply might be a useful rule when bying an SE (to return to the OP's topic).
 
John M Robinson said:
Kevin and Arthur,
For example would I be testing my luck by buying a 8x32 SE, sight unseen?

Thanks,
John
Click to expand...

John,

I recommend that a binocular should not be bought, sight unseen. However, some vendors, do have a good return policy which allows a little "test driving."
You also bring up nasal relief, meaning can the binocular accommodate both your IPD and the size of your nose? Some binoculars fail to fit everyone, for a variety of reasons.

Happy bird watching,
Arthur
 
Last edited:
I second Pinewoods advice and I actually prefer a buy and return strategy with an more extended evaluation. I find store evaluations not not be be a great deal of help aside from "That's crap" immediate evaluation. A thourgh evaluation followed a buy a day or two's birding gives you the answer to "keep or return".

I think I've narrowed down some of the circumstances of when the SE causes blackouts: I'd worry more about it if you are myopic or if you have a flat face ("shallow set" eyes. I think with your prescription you are less likely to have problems (at least that's my prediction).

The narrow IPD though is a problem. You do have to get these bins centered on your pupils (that's the spherical aberration of the exit pupil part). That's the thing that might sink you.

So for you it's a coin toss ... so be sure you can return them.

Perhaps you can find a local birder with an SE. You would know after a few minutes use.

I think the rubber eyecups are better for "nasal relief": the twist ups do tend to be bigger in diameter and more of a problem.

All of the SE's should be the same with blackouts. They have a classic minimalist design: they all share the same prism housing and eyepieces. So they all have the same eye relief. They all have the same exit pupil size. The only thing that changes is the objective lens and tubes so the magnification and lens diameter increase at the same rate.

If you have an SE and it does or does not give you blackouts could you say something about your vision, eyeglasses, or your face shape? We might be able to wrap this one up!
 
Kevin Purcell;1352843) All of the SE's should be the same with blackouts. They have a classic minimalist design: they all share the same prism housing and eyepieces. So they all have the same eye relief. They all have the same exit pupil size. The only thing that changes is the objective lens and tubes so the magnification and lens diameter increase at the same rate. If you have an SE and it does or does not give you blackouts could you say something about your vision said:
That information helps because I do own and use the 10x42SE without any blackout issues whatsoever. It is actually less finicky than my 8x42 Ultravid.

Thanks,
John
Click to expand...
 
It seems my question is leading on to a lot of other things not necessarily related to the subject. Maybe an other thread is in order?

Meantime appreciate those answers received. Basically don't go for the smaller sizes eventhough latest spec. Be careful with second hand and there are some pretty good alternatives out there. Thanks for the local chain information, I'll look them up.

I do appreciate that it is best to test and try before you buy, but I am particular to the performance during dawn and dusk. Not a lot of shops are open then or will allow a test and there are too many options out there to try every one else's bino's.

The quest continues! Thanks, Rene.
 
Mostly, we use friendly on line sellers so we can exchange two or three times till we are happy. Most models are not in my local stores. Besides, they know me by now. Here comes the binocular guy.
 
ReneZ said:
I do appreciate that it is best to test and try before you buy, but I am particular to the performance during dawn and dusk
Click to expand...

Probably should go for a magnification of 7x or 8x and 'big' objective lenses if this is the case.
 
KorHaan said:
....
I could say all kinds of nasty things of FL's too, but let's say I'm glad I sold mine and bought Minox BL's; four times cheaper, and well-designed separate diopter and focus. ...
Click to expand...

What is more important, optics or looks? On the first topic, FLs sure are better, by far, in my opinion. But I agree about the lousy Zeiss quality controls.
And the diopter is far from optimal as well. Interesting that Leica has no problem with their way they have solved the combination of diopter and focus.
 
I don't care about the looks, but am looking at a good pair that fits the bill and will allow me to see things in the early or late hours. I like what I read about the Minox HG, but understand there are two models APO and without APO. It is unclear (to me) if the comments refer to the first or the latter. All thanks for the advise so far!! Cheers, Rene.
 
Hello ReneZ,

Most of our American readers may not realize how long twilight can be in the higher latitudes. A 8x42 might give only a 'couple of minutes' more viewing than an 8x32, in Missouri, 39ºN, but it may give much more viewing time in Perth, 53ºN.

Happy bird watching,
Arthur
 
Pinewood said:
Hello ReneZ,

Most of our American readers may not realize how long twilight can be in the higher latitudes. A 8x42 might give only a 'couple of minutes' more viewing than an 8x32, in Missouri, 39ºN, but it may give much more viewing time in Perth, 53ºN.

Happy bird watching,
Arthur
Click to expand...

Too true, Arthur...and this is compounded by the fact that in Humid Temperate Climes (such as here), "Twilight"-conditions may start long before sundown if there´s low-lying cloud. Sometimes even at 2pm in the afternoon, at this time of year (low sun, gun-metal cloud), I feel a need for binos that transmit as much light as possible.
 
Indeed, something suitable for low-light conditions. 7 or 8 x 42/43/44/45 with very good low-light qualities. Something must be out there that doesn't break the bank as I'm not ready (yet) to steal the study funds of the kids. Appreciate your help! Cheers, Rene.
 
Warning! This thread is more than 15 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Similar threads

B
Broke college student looking for binocular recommendations ( less than £100) UK
Replies
13
Views
746
Mike Crawley
Mike Crawley
D
New binoculars under 200€
2
Replies
32
Views
2K
Davide_Videvitt
D
B
Which monocular as a substitute for binoculars...?
2 3
Replies
41
Views
2K
wm.wragg
W
A
Entry - Midrange Binocular Recommendation ($500)
2
Replies
22
Views
2K
Binovehje
B
D
  • Locked
Glare Monsters!
21 22 23
Replies
445
Views
24K
Jos Stratford
Jos Stratford

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Back
Top