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Old Friday 20th January 2012, 02:41   #51
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Hi Steve

On the Fury, I lightly touch the eye cups to my glasses. On the Minox Porro I push hard enough to set the glasses back a little. I think you could get by without the cups, but I get a good bit of stability from being direct coupled to them. For some reason, I can't get a sharp image on the right side with any binocular without my glasses on. With them on, sharp as a tack. If I could be without the glasses, I would love to use the winged eye guards on all of my binos.

Bruce
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Old Friday 20th January 2012, 04:55   #52
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I have to have eye cups and I need them fully extended while braced under my eyebrows or I get kidney beaning and even worse as the eye cups get shorter and ultimately fully closed.

And I need to brace them under my eyebrows. That way when I move my head the binocular moves with it. I can't understand how people use binoculars just holding them away from their eyes.

I've been trying to use binoculars with the eye cups in their various down positions as illustrated in the threads here (and even without the eyecups on my Swarovskis) while holding them away from my eyes and I really can't see any wider or better FOV. I really don't understand this concept of being "immersed" in the view and not seeing any tunnel.
I have never used a binocular that did not have this "tunnel" effect in it's view.

Maybe I don't understand the explanations or maybe I am doing something wrong.

Bob

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Old Friday 20th January 2012, 05:54   #53
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Eyeglasses as an optimal interface device

Quote:
Originally Posted by bh46118 View Post
If you have 20-20 vision, would you still get the same positive effect by using your binoculars with a pair of glasses in which the lenses haven't any prescription ? Does that make any sense ?

Bruce
Hi Bruce,

I believe so. It does make sense. The reason it might seem a bit odd is that we traditionally use eyeglasses either to improve vision, or to protect it (e.g., safety glasses, shooting glasses, sunglasses, etc.), but not to act as a preferred interface for visual instruments. Mostly, they are thought of as an annoyance to be dealt with in some way or another. Your question, however, provides a segway into a fundamental issue: What is the optimal way to interface the human eye with binoculars for the purposes of birding? (I limit this to birding for the simple reason that military and astronomy uses place very different demands on the user, and, therefore, need to be addressed within their own frameworks.)

All binoculars have a fixed "eye point," which is located some distance away from the ocular. To obtain an optimal retinal image through the instrument the pupil should be placed at the same distance as the eye point, and parallel to eye lens. So much for optics design. There are no principles that address how the pupil should be placed at the eye point! Nor are there design principles that address either the perceptual or behavioral aspects of "the view" that results from varied approaches.

Convention dictates that all binoculars are equipped with eyecups of some sort, e.g., hard phenolic, soft rubber, or extendable tubes. These all at least partially occlude side light, which many believe is necessarily beneficial. But for a variety of reasons this may not be completely true, as we are now slowly coming to discover that an unmagnified periphery added to the magnified center may have important benefits for psychological "immersion" and birding task performance.

Getting to the practical, one might deliberately buy non-prescription clear optical glasses to supplement birding, of course, but a relatively new technology provides the potential for reaching a higher level of human-system integration: transition lenses. These little beauties darken in proportion to the ambient light and appear to do a very effective job optimizing the amount of light presented to the retina, — which fixed density sunglasses do not. To my experience they can be used effortlessly with binoculars, which I assume would also be true without a prescription. In other words, this technology may provide the ideal adaptive sunglass that seamlessly supports birding applications.

This discussion branches off into the area of sunglass effectiveness for vision, which I've been looking into on and off, but won't comment much about at this point. The evidence I have seen, though, supports the thesis that transition eyeglasses, fit to allow proper eye point placement, can definitely enhance the joys of birding. What I used to think of as a disadvantage having glasses turns out to be a bonus.

Maybe //LS has some professional thoughts on the subject.

Ed
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Old Friday 20th January 2012, 12:25   #54
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The idea with the PFOV concept wasn't to add confusion or look for something that is not a problem to you.
On the contrary, the idea is to complement the AFOV factor. I hope it's clear that I regard the 56° AFOV Fury very walk-in despite the modest AFOV.

Thus, the goal is as follows:

1) To show that certain binoculars can deliver a much more "open" view than could be expected from the calculated AFOV

2) To find another of the not-so-apparent like/dislike factors that sometimes influence the decision.

Ed,

personally I'm not very fond of photochromic spectacle lenses. Eyen the grey ones seem to distort the colors to me. But that's just another example we are all different and have different preferences.

//L
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Old Friday 20th January 2012, 17:36   #55
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Thanks Ed

Using my eyeglasses makes a bigger difference in view for me than the differences in optics themselves. The only other thing I know of that gives another huge step up in optimization is either a monopod or a tripod, but with the obvious limitations in mobility.

Bruce





Quote:
Originally Posted by elkcub View Post
Hi Bruce,

I believe so. It does make sense. The reason it might seem a bit odd is that we traditionally use eyeglasses either to improve vision, or to protect it (e.g., safety glasses, shooting glasses, sunglasses, etc.), but not to act as a preferred interface for visual instruments. Mostly, they are thought of as an annoyance to be dealt with in some way or another. Your question, however, provides a segway into a fundamental issue: What is the optimal way to interface the human eye with binoculars for the purposes of birding? (I limit this to birding for the simple reason that military and astronomy uses place very different demands on the user, and, therefore, need to be addressed within their own frameworks.)

All binoculars have a fixed "eye point," which is located some distance away from the ocular. To obtain an optimal retinal image through the instrument the pupil should be placed at the same distance as the eye point, and parallel to eye lens. So much for optics design. There are no principles that address how the pupil should be placed at the eye point! Nor are there design principles that address either the perceptual or behavioral aspects of "the view" that results from varied approaches.

Convention dictates that all binoculars are equipped with eyecups of some sort, e.g., hard phenolic, soft rubber, or extendable tubes. These all at least partially occlude side light, which many believe is necessarily beneficial. But for a variety of reasons this may not be completely true, as we are now slowly coming to discover that an unmagnified periphery added to the magnified center may have important benefits for psychological "immersion" and birding task performance.

Getting to the practical, one might deliberately buy non-prescription clear optical glasses to supplement birding, of course, but a relatively new technology provides the potential for reaching a higher level of human-system integration: transition lenses. These little beauties darken in proportion to the ambient light and appear to do a very effective job optimizing the amount of light presented to the retina, — which fixed density sunglasses do not. To my experience they can be used effortlessly with binoculars, which I assume would also be true without a prescription. In other words, this technology may provide the ideal adaptive sunglass that seamlessly supports birding applications.

This discussion branches off into the area of sunglass effectiveness for vision, which I've been looking into on and off, but won't comment much about at this point. The evidence I have seen, though, supports the thesis that transition eyeglasses, fit to allow proper eye point placement, can definitely enhance the joys of birding. What I used to think of as a disadvantage having glasses turns out to be a bonus.

Maybe //LS has some professional thoughts on the subject.

Ed
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Old Friday 20th January 2012, 19:00   #56
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Quote:
Originally Posted by bh46118 View Post
Thanks Ed

Using my eyeglasses makes a bigger difference in view for me than the differences in optics themselves. The only other thing I know of that gives another huge step up in optimization is either a monopod or a tripod, but with the obvious limitations in mobility.

Bruce
Bruce,

We agree again. I use a shooting stick modified for the binoculars to perch on top. But it only works well with binoculars that have chubby tubes. Shown below is the most recent adaptation for my new 8x42 SLC HD.

//LS.

I don't think PFOV will have much utility for folks who don't use corrective eyeglasses. If they happen to like photochromatic lenses I can testify that it all works out very nicely. I've got a birding friend who says the same thing, and he surprised me by also using progressive lenses. (Those things drive me crazy.) Neither of us are even aware of the change in lens darkness and the view seems appropriately bright under a wide range of ambient conditions. For me, it's much better than before I used glasses, because of the wide perceived field and also the controlled illumination. IMHO, the combined technology is amazing.

Fixed density sunglasses often present a problem: one second you need them and the next you don't — a real nuisance. I'm willing to bet that most non-eyeglass users would simply take them off, eyestrain or not, rather than fool around with PFOV. So the availability of non-prescription photochromatic (transition) sunglasses would be an idea, although I'm not aware that they are currently marketed.

Me thinks I've gone as far as I can on this topic. Starting to sound like a salesman.

Regards,
Ed
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Old Friday 20th January 2012, 19:37   #57
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Thanks Ed


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Bruce,

We agree again. Ed
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Old Friday 20th January 2012, 20:15   #58
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Quote:
Originally Posted by elkcub View Post
Bruce,

We agree again. I use a shooting stick modified for the binoculars to perch on top. But it only works well with binoculars that have chubby tubes. Shown below is the most recent adaptation for my new 8x42 SLC HD.

//LS.

I don't think PFOV will have much utility for folks who don't use corrective eyeglasses. If they happen to like polychromatic lenses I can testify that it all works out very nicely. I've got a birding friend who says the same thing, and he surprised me by also using progressive lenses. (Those things drive me crazy.) Neither of us are even aware of the change in lens darkness and the view seems appropriately bright under a wide range of ambient conditions. For me, it's much better than before I used glasses, because of the wide perceived field and also the controlled illumination. IMHO, the combined technology is amazing.

Fixed density sunglasses often present a problem: one second you need them and the next you don't — a real nuisance. I'm willing to bet that most non-eyeglass users would simply take them off, eyestrain or not, rather than fool around with PFOV. So the availability of non-prescription polychromatic (transition) sunglasses would be an idea, although I'm not aware that they are currently marketed.

Me thinks I've gone as far as I can on this topic. Starting to sound like a salesman.

Regards,
Ed
Ed:
This is an interesting topic, and here is another thing that goes along with your sunglasses wants and needs.
I have several pairs of Serengeti sunglasses, both regular and polarized, that are "photochromic" and do
change to some degree with changing light levels.
Sunglasses can play with light and colors to a large degree, and when used with binoculars can be interesting indeed.
For myself, I don't use glasses when viewing, and I also do not care for using sunglasses either.

I am posting a link, and click on "technology", you can move the lens around
to see how it changes the view.

http://www.serengeti-eyewear.com/main.aspx

Jerry

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Old Friday 20th January 2012, 20:19   #59
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Quote:
Originally Posted by elkcub View Post
Hi Bruce,
Convention dictates that all binoculars are equipped with eyecups of some sort, e.g., hard phenolic, soft rubber, or extendable tubes. These all at least partially occlude side light, which many believe is necessarily beneficial. But for a variety of reasons this may not be completely true, as we are now slowly coming to discover that an unmagnified periphery added to the magnified center may have important benefits for psychological "immersion" and birding task performance.
Ed
Using binoculars with the eyecups collapsed and with no spectacles is not very convenient because the support to prevent hand-shake effects is lost, and blackouts are likely to occur. But like you write, the peripheral vision adds to the birding performance.

It's easier to keep the binocular in front of the eyes for longer time, and you'll find speedy warblers more easy.
The total exclusion of peripheral vision that happens with the eyecups extended makes these things harder.
Imagine a situation where you use a camera through a hole in a black blanket rather than the ordinary way. It's a lot harder to find the object, right?

EDIT: And I agree with you, Ed, and with bh46118
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Old Friday 20th January 2012, 22:06   #60
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Quote:
Originally Posted by NDhunter View Post
...

I am posting a link, and click on "technology", you can move the lens around
to see how it changes the view.

http://www.serengeti-eyewear.com/main.aspx

Jerry
Very interesting. Im glad to hear there's more than one manufacturer of photochromatic. These appear to be non-prescription sunglasses? The stuff I use is called "transition", and it may have more neutral color bias, ... at least the gray ones. This is my second pair and the responsiveness has improved a great deal. Take a look. You might want to use eyeglasses while birding after all.
http://en-us.transitions.com/en/defa...FQ5lhwodyCoHCQ

Thanks for starting this thread //LS.

Ed
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Old Friday 20th January 2012, 22:40   #61
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Quote:
Originally Posted by elkcub View Post
Very interesting. Im glad to hear there's more than one manufacturer of photochromatic. These appear to be non-prescription sunglasses? The stuff I use is called "transition", and it may have more neutral color bias, ... at least the gray ones. This is my second pair and the responsiveness has improved a great deal. Take a look. You might want to use eyeglasses while birding after all.
http://en-us.transitions.com/en/defa...FQ5lhwodyCoHCQ

Thanks for starting this thread //LS.

Ed
Ed:
I like sunglasses with the plastic frames, with curved lenses. Then I find
the eyerelief is too much, and so they don't work so well for me, with binoculars.

Jerry
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Old Friday 20th January 2012, 23:06   #62
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AFAIK, there are only three manufacturers of organic photochromic spectacle lenses.
These are Transitions, who market their brand directly to consumers although they are not making the very lenses, Hoya and Rodenstock who are optical lens factories.

For silicate lenses, I only know of Schott, but there may be others as well.
Typically, the newer generations of organic lenses are very fast in their response and have a wide range of activation, from almost clear to a full 80 or 85 percent absorption.
The silicate lenses are typically slower and have a narrower range of activation.

The effect is triggered by UV radiation and they will not be very dark when driving a car unless it's a convertible with the roof down. Outside, they will activate, but in overcast weather they will be disproportionally dark because of the greater UV portion of the total light amount.
They will also be darker in colder weather because low temperature will delay the "bleaching" of the lens caused by white light.
The degree of activation is decided by the amount of UV radiation for darkening, the amount of white light for bleaching and the temperature.

Mine were Hoya lenses, and while looking neutral grey they peaked some colors quite a bit towards reddish.

Prescription lenses can be had without dioptric power and the price would be the same as for lenses with power.

//L
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Old Saturday 21st January 2012, 00:25   #63
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Quote:
... Typically, the newer generations of organic lenses are very fast in their response and have a wide range of activation, from almost clear to a full 80 or 85 percent absorption.
That's the kind I like, Hoya. There is a valid reason for attenuating high intensity blue, so that may be part of the reason for a red bias. Swarovski also seems to do this with their transmission curves, and I'm sure they could do otherwise if they wanted to.

Take note, Jerry, plastic frames with curved lenses are strictly passé! Next you'll tell me they have to be mirrored.

Ed
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Old Saturday 21st January 2012, 00:43   #64
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That's the kind I like, Hoya. There is a valid reason for attenuating high intensity blue, so that may be part of the reason for a red bias. Swarovski also seems to do this with their transmission curves, and I'm sure they could do otherwise if they wanted to.

Take note, Jerry, plastic frames with curved lenses are strictly passé! Next you'll tell me they have to be mirrored.

Ed
Ed:
I wear sunglasses for protection against the sun's rays, and I do not care
about looks, but need styles with wide temples.
I am outdoors a lot, and have to take precautions, as I have had some skin cancer, in that area.
Probably more than you wanted to know, but just a reminder here for everyone here, to take precautions, and protect yourself.

Jerry
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Old Saturday 21st January 2012, 00:44   #65
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Jerry,

Sorry to hear that. Forgive me please, I was just joking.

Ed
PS. I'm a three time cancer survivor myself.
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Old Saturday 21st January 2012, 00:48   #66
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Ed:
I wear sunglasses for protection against the sun's rays, and I do not care
about looks, but need styles with wide temples.
I am outdoors a lot, and have to take precautions, as I have had some skin cancer, in that area.
Probably more than you wanted to know, but just a reminder here for everyone here, to take precautions, and protect yourself.

Jerry
Me too Jerry. I know what you mean.
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Old Saturday 21st January 2012, 01:33   #67
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My lenses are rather large, not the tiny lenses that are currently in style. Makes me look like a nerd, but there is plenty of surface area for even the largest eye cups.

Bruce
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Old Saturday 21st January 2012, 15:14   #68
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Back on topic with new images showing a simple experiment.
This explanation of PFOV is not optical, but very much shows what happens in the visual field.

The images would clearly show it, but if you want to make the experiment it only takes a paper tube and a round cardboard roundel with a hole in the center.
Of course there's no lenses or magnification involved, so differences in AFOV and PFOV will solely depend on the diameter of the tube and the hole.

The outer, open end of the tube is the angular field. If you look through the tube before attaching the roundel, you will see a certain portion or cut-out of the reality in life-size, and the walls of the tube will hide the rest.
A wider and/or shorter tube will expand the FOV.

The hole's diameter does NOT correspond to the exit pupil size or ocular lens size, but to the eye relief.
If the hole is smaller, you will need to get closer to see the whole FOV, but if it is bigger, you can hold the tube further away.

In the first image, the roundel barely hides the walls of the tube. If held closer, like in the second image, you will see more of the walls.
In addition, the outer diameter of the roundel will occupy more of your visual field, thus decreasing the free angle of sight.
Here, it is obvious that the angular size of the obscuration from the fieldstop to the outer edge of the roundel is greater when the bins/tube are held too close.

The third image shows what happens when you're too far from the hole - you will of course not see as much of the field.

The fourth image (upper right) shows a larger diameter tube with a smaller hole. This corresponds to a larger FOV with a shorter eye relief compared to the first ("Ideal") image. Pretty much of the visual field gets obscured by the large diameter of the roundel, but the image or FOV portion is larger.

The last image (lower right) shows that if you use a cone-shaped tube, nothing happens with the FOV.
Surprisingly little, but still some, happens with the free angle of sight. This is because the tiny eye relief means than the ocular end of the cone occupies much of the visual field.
Image #4 and #5 should explain why Frank's two porros, although similar, feel different. I believe it's a matter of external differences.

Somebody put the question if binocular's makers shouldn't make separate models for spectacle wearers and non-bespectabled.
Undeniably, many models seem to be much of compromise, and the way to handle the downsides of sufficient eye relief for them, is to use twist-up eyecups.
That is not the perfect way to do it, since they obscure much of the visual field.

//L
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Old Saturday 21st January 2012, 22:12   #69
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//LS,

Just read this a second ago. At first blush it seems very clever and makes a lot of intuitive sense, but it will take me a while to satisfy myself that it generalizes to a universal telescope interface.

In any event, it's quite inventive and very interesting. Congratulations!

There are relevant perceptual phenomena that can also be demonstrated with your model, which may help to explain some subjective reports on this and earlier threads.

Good thinking!

Ed
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Old Saturday 21st January 2012, 22:26   #70
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Thanks Ed!
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Old Saturday 21st January 2012, 22:45   #71
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I have been working on a somewhat different approach shown in the preliminary drawing below. But I'm not sure where it's leading. I had something in mind. Wait ...

Ed
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Old Saturday 21st January 2012, 23:08   #72
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The scaling may be off a bit, but the geometry suggests (a) that the bulk of the binocular is not in the visible field, even a Porro, and (2) an appreciable amount of unmagnified information within the 120º overlap area of the retina can enter though the corrective eyeglasses beyond the annulus.

For the most part, unmagnified information beyond the eyeglasses themselves probably projects onto the 30º monocular fields on either side. This will vary with the eyeglass diameter. Finally, because of the steep angles involved, very little size change or fore-aft movement can result in a large change in how the full field appears. Hence, each individual may take a bit of fitting before everything works just right.

I'm still fascinated by whether or how the brain integrates magnified and unmagnified images in the overlap area.

Ed
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Old Saturday 21st January 2012, 23:51   #73
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While I find this thread quite interesting, I find most of the diagrams quite optimistic and over simplified. I took a pair of 8x36 Bushnell Legend Ultra HD's and set them up on a tripod at a distance of 10 ft from a measuring tape. With the eyecups collapsed and my glasses on I could see a width of 17", and glancing to the side it was 68" from the left fieldstop to where the obstuction of the eyecup and bino ended. So in this test I am seeing the 426 ft TFOV of the bino but it is obscured by an additional 1700 ft TFOV on each side before the peripheral vision is unobstructed. Handholding the bino would add even more of an obstucted FOV to the sides than the 1700 ft.

While I would not say that I have an enhanced or greater perceived FOV with glasses, I would acknowledge that with glasses I can see more of the outer peripheral. Perhaps a better term than PFOV in my mind might be spatial awareness.

Tom
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Old Sunday 22nd January 2012, 00:22   #74
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The scaling may be off a bit, but the geometry suggests (a) that the bulk of the binocular is not in the visible field, even a Porro, and (2) an appreciable amount of unmagnified information within the 120º overlap area of the retina can enter though the corrective eyeglasses beyond the annulus.

For the most part, unmagnified information beyond the eyeglasses themselves probably projects onto the 30º monocular fields on either side. This will vary with the eyeglass diameter. Finally, because of the steep angles involved, very little size change or fore-aft movement can result in a large change in how the full field appears. Hence, each individual may take a bit of fitting before everything works just right.

I'm still fascinated by whether or how the brain integrates magnified and unmagnified images in the overlap area.

Ed
Hm, tricky one...
Your drawings show a front view towards the eye and a view from the side.
Mine have only shown the view from above, where the visual field expands towards right and left. And, yeah, a cycloptic view to be correct, where no nose is in the way and left and right eye are made one.

At the moment, I have no porro in my possession, but frankly I'd guess that the prism housings + the hands will intrude on those, the lateral parts of the visual field.
More so with shorter physical length of the oculars, or with longer eye relief where the diameter of the eyepiece will not hide them.
But I may be wrong, it has occurred before.

The spectacle lenses' width is of interest only for the lateral parts of the visual field. But nobody will receive a focused image of the medial parts of the bins, either because of the short distance (1" to 2") or because they are way out of the eye's zone of sharpness when you look through the bins.
The zone of sharp vision sits in the 2 degrees absolute center of the visual field.

The height of the spectacle lenses might be of significance should they allow to glance upwards when the bins are held in place, provided their ocular diameter is not too large. When looking straight forward, the peripheral parts of the lenses carry no additional information that is useful for the sense of vision.
Extremely large lenses would however be hard to wear, and grease from the eyebrows would deposit on them immediately.

Possibly, a thick spectacle frame might pose some noticeable intrusion. It has happened to me, but it was actually in the very image after being pushed-up by the bins.

//L
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Old Sunday 22nd January 2012, 00:43   #75
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This is an interesting optical illusion that I've seen a few times. It's very vivid.

I think the issue here is where the final aperature that just matches the vignetting aperture.

I've even seen this effect on "narrow" field bin with pop up eyecups. If you set the eyecups just right (just about vignetting the FOV) it appeared a lot bigger.
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I think the issue here is where the final aperature that just matches the vignetting aperture.
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