Are Wide Angle Bins Brighter? (1 Viewer)

Chosun Juan · Jan 14, 2015

typo said:
More light will pass through the exit pupil with the wider field of view but it will be focussed on a proportionally larger area of the retina so the light per unit area or brightness stays the same.

David

David,

Thanks for the elegant explanation. I came to this realization after prompting by Ed last time we discussed this, but couldn't quickly find the thread again, so didn't post the a-ha! moment. :brains:

Ed was starting to say some very interesting stuff about newly discovered in-between photon receptor sites or some such ..... I hope he picks up on this and continues on ..... :cat:

Apart from the actual optio-electrical physiology, I'm thinking two additional things in relation to this -- both quasi psychological .....

(i) A wider FOV (AFOV) during bright conditions (ie. The pupil is effectively stopped down smaller than the binoculars EP) will 'appear' brighter since the eye itself will add less off-axis and peripheral aberrations (astigmatism etc) -- thus giving a sharper view over more of the field which may 'appear' brighter ......

(ii) A wider FOV (AFOV) during those same conditions AND in concert with very thinly framed eyepieces may 'appear' brighter in accordance with Looksharp's PFOV hypothesis ...... (where is LS anyway? .... off for a holiday with Pompadour?? ---- can't be with Brock since the prodigal son has returned with a double Nikon barrel !!!

)

Thoughts by the optical mavens would be welcome .....

Ps. David - what is the significance of the 450 nm wavelength you mentioned, and what are the details and source for that information? :cat:

Chosun :gh:

typo · Jan 14, 2015

Chosun,

I'd been hunting around various colour theory and colour perception articles trying to find an explanation why some binos, particularly those with very good short wavelength transmission appear to my eyes to produce a richer or possibly brighter colour palate. I found something called the Helmholtz-Kohlrausch effect that appear to at least to offer a partial explanation. I posted a bit more here:

http://www.birdforum.net/showpost.php?p=3149517&postcount=63

It looks like you might have muddled a couple of things up in point one. A wide field of view is not altered by the pupil of the eye contracting. When the pupil is dilated in low light, visual acuity is poor, when the light levels are higher your acuity is better and the DOF improves. I'd agree a sharp image and wider sweet spot appears brighter than a more blurred image, so when it is brighter, the view looks brighter.... but that's probably not helping.:-O

David

eddy the eagle · Jan 14, 2015

I am no scientist or ocular expert but the common sense I see here is,if 100% light goes through the objectives and there is no lenses to go through then 100% light comes out the other end.Add lenses etc and this exit light is diminished depending on coating etc.This is what diminishes the brightness and this is why binocular manufactures try to make the highest light transmission possible....Eddy

Gijs van Ginkel · Jan 14, 2015

Eddy,post 23,
Unfortunately life is more complicated, since you forget how our eyes fool us by deciding that one color is brighter than another, see Davids reference in a previous post.
Gijs

Chosun Juan · Jan 14, 2015

typo said:
Chosun,

I'd been hunting around various colour theory and colour perception articles trying to find an explanation why some binos, particularly those with very good short wavelength transmission appear to my eyes to produce a richer or possibly brighter colour palate. I found something called the Helmholtz-Kohlrausch effect that appear to at least to offer a partial explanation. I posted a bit more here:

http://www.birdforum.net/showpost.php?p=3149517&postcount=63

It looks like you might have muddled a couple of things up in point one. A wide field of view is not altered by the pupil of the eye contracting. When the pupil is dilated in low light, visual acuity is poor, when the light levels are higher your acuity is better and the DOF improves. I'd agree a sharp image and wider sweet spot appears brighter than a more blurred image, so when it is brighter, the view looks brighter.... but that's probably not helping.:-O

David

David,

That was the point. The FOV (or brightness for that matter) does not change, just the part that appears sharp to the eye + bin system which may then 'appear' brighter as a psychological illusion. There's just something about the opacity of the blurry part of the field that seems duller than particularly the transparent central view of a good porro. (Swift Audubon 8.5×44 ED is a good case in point) :t:

Chosun :gh:

Troubador · Jan 14, 2015

Gijs van Ginkel said:
Eddy,post 23,
Unfortunately life is more complicated, since you forget how our eyes fool us by deciding that one color is brighter than another, see Davids reference in a previous post.
Gijs

Gijs

Talking of life being more complicated. Remember your saying 'to measure is to know' ?

Doesn't work with sub-atomic particles in the sense that measuring speed and position at the same time seems impossible. Now, is that just about as off-topic as is possible? :-O

Lee

Gijs van Ginkel · Jan 14, 2015

Lee, post 26,
Yes, you are right and I think about the cat of Schrödinger, who was kept in a box and nobody was sure whether he was there or not and about Stephen Hawkins who threatened to shoot himself if we were referring to this magic cat. Life is full of surprises and unexpected things, I was confronted with it when our neighbours cat died suddenly by a small hole in his head and we did not hear the sound of the shot and we also were not able to get a picture of Hawkins when he disappeared around the corner although we were not sure whether it was him or our prime minister, who does not like cats. So you made me uncertain whether to measure is to know, perhaps we should go back to the Middle ages and start to make gold again from mixing sand with potassium or sodium and suddenly finding that something emerged we could look through (actually that is how looking glasses were discovered, Alice told me about it when we met in wonderland whre she saw al kinds of colors before her eyes, the basis of our color theory, and all that because her founding father was a pastor in the English village of Daresbury, where they established a synchrotron to generate light of all kinds of colors). Is that relevant to binoculars?
Of course, but you will understand that directly,
Gijs

denco@comcast.n · Jan 15, 2015

Troubador said:
In response to Bruce's suggestion (see below) I will demonstrate my optical ignorance (again) by asking a naive question.

Quote:
Originally Posted by Troubador View Post
Bruce I would lay money (especially somebodyelse's ) that the big field of view contributed a large portion of the impression of brightness too simply because there is so much sky in the view.

Lee
A good point. That is something I have wondered about in the past when doing comparisons for brightness. That might make for a good topic of discussion in a new thread. /INDENT]

When I started out buying bins the adverts stated that 42s were brighter than 32s and the impression given was that the 42 mm objective lenses grabbed more light. At the time therefore I imagined that the view through a 42 had more light per square mm than that from a 32. I don't recall anything about brightness being exit pupil - dependant. In fact I don't recall anything about exit pupils at all, but maybe I skipped over this concept not understanding what it was.

OK so I understand today that brightness is largely dependant on exit pupil size apart from the issue of high transmission glasses which do allow more photons per square mm to pass, even if perception of the benefit is controversial and may vary from person to person.

But what about wide-angle eyepieces? Don't they capture a larger area of the image created by the objective lenses and squeeze it into the exit pupil? And if so doesn't this necessarily mean that more photons per square mm are squeezed into the exit pupil. In short, doesn't this mean that wide-angle bins are brighter??

OK, I've stuck my head up above the parapet, so start shooting :smoke:

Lee

The two things that determine brightness in a binocular are Exit Pupil diameter and number and quality of coatings. That's it. It is not complicated. That is why the alpha's are brighter because they have better coatings. Prism type use to affect transmission a little but not much anymore with the dielectric coatings they are losing very little light on any of the prisms.

Chosun Juan · Jan 15, 2015

Gijs van Ginkel said:
Lee, post 26,
Yes, you are right and I think about the cat of Schrödinger, who was kept in a box and nobody was sure whether he was there or not and about Stephen Hawkins who threatened to shoot himself if we were referring to this magic cat. Life is full of surprises and unexpected things, I was confronted with it when our neighbours cat died suddenly by a small hole in his head and we did not hear the sound of the shot and we also were not able to get a picture of Hawkins when he disappeared around the corner although we were not sure whether it was him or our prime minister, who does not like cats. So you made me uncertain whether to measure is to know, perhaps we should go back to the Middle ages and start to make gold again from mixing sand with potassium or sodium and suddenly finding that something emerged we could look through (actually that is how looking glasses were discovered, Alice told me about it when we met in wonderland whre she saw al kinds of colors before her eyes, the basis of our color theory, and all that because her founding father was a pastor in the English village of Daresbury, where they established a synchrotron to generate light of all kinds of colors). Is that relevant to binoculars?
Of course, but you will understand that directly,
Gijs

Gijs ! :t: Bravo !! :clap:

I'll have what you're having !!!

. :hippy: :bounce: (o)<

:cat:

Chosun :gh:

denco@comcast.n · Jan 15, 2015

Chosun Juan said:
Gijs ! :t: Bravo !! :clap:

I'll have what you're having !!! . :hippy: :bounce: (o)<
:cat:

Chosun :gh:

Are you eating Magic Mushrooms down there in the forest?

Troubador · Jan 15, 2015

Gijs van Ginkel said:
Lee, post 26,
Yes, you are right and I think about the cat of Schrödinger, who was kept in a box and nobody was sure whether he was there or not and about Stephen Hawkins who threatened to shoot himself if we were referring to this magic cat. Life is full of surprises and unexpected things, I was confronted with it when our neighbours cat died suddenly by a small hole in his head and we did not hear the sound of the shot and we also were not able to get a picture of Hawkins when he disappeared around the corner although we were not sure whether it was him or our prime minister, who does not like cats. So you made me uncertain whether to measure is to know, perhaps we should go back to the Middle ages and start to make gold again from mixing sand with potassium or sodium and suddenly finding that something emerged we could look through (actually that is how looking glasses were discovered, Alice told me about it when we met in wonderland whre she saw al kinds of colors before her eyes, the basis of our color theory, and all that because her founding father was a pastor in the English village of Daresbury, where they established a synchrotron to generate light of all kinds of colors). Is that relevant to binoculars?
Of course, but you will understand that directly,
Gijs

Gijs

Superb!

However I don't think it was Alice that you saw, it was Lucy in the sky (with diamonds). Lucy used to have her own comedy show in the USA until she was discovered by John Lennon who was in love with Cynthia, the Greek goddess of Light.

Amazing work by archaeologists at the Cynthian Temple in Greece have discovered that the Greeks knew all about the Higg's Boson (although it was a different Higgs) and about Higg's Prism which was discovered in the first known binoculars that were found fossilised at Neanderthal in Germany.

The Higgs Bins (as they are technically known) were designed by Zeiss in the Jurassic Epoch but due to delays in getting it into production they were fossilised before they could be launched on the market, which was a shame. Still, that could never happen today :-O.

Lee

Troubador · Jan 16, 2015

WJC said:
* trying to compare two binos with the same aperture, magnification, and quality is senseless—kinda like trying to ice skate UPHILL! There are just TOO MANY VARIABLES.

Bill

Wild Bill

In many ways you are right from a technical evaluation stand-point. However as packages of bundles of capabilities and characteristics, available to purchase at a given price, buyers do make comparisons that are valid on a personal level even if they are along semi-subjective lines.

Thus some comparisons that people are faced with before they buy might include: do I prefer the fast focus on this model or the flat field of this other one, at these prices? Or do I want the extra brightness of this one or the lighter weight of the other?

These are all valid personal buying choices just like deciding whether I would prefer to eat a banana just now or an orange :-O

Lee

WJC · Jan 16, 2015

:cat:Apologies to all:

I tried hard to stay away from this thread; I just wasn’t man enough. Sorry!

As most folks in astronomy and telescope making know, “A longer focal ratio can hide a multitude of sins,” and, whether we like it or not, our eyes (with all their faults*), are part of our binocular system.

In low light, the average eye is working at about f/4. That is, in the vernacular of UAs Optical Sciences Center, “bad Ju Ju.” When our pupils are stopped down in bright daylight, they may reach f/11 or . . . “good Ju Ju.”

A wide-angle has little to do with brightness. For more optical scripture: “The objective giveth, and the eyepiece taketh away.”

The larger the objective, the more light can enter the instrument, and the brighter the image can be at a given opening for our biological pupils. Because, as magnification increases image brightness decreases, a bino with a bright, crisp image at 7-8 power, will be dimmer and somewhat fuzzier at 16-20 power, although the binoculars have exactly the same clear aperture. The attached photo illustrates how this works. At a distance of 1 foot, a light source has a brightness of X, but when the distance is only doubled, the brightness is only ¼ X. Thus, it is easy to see how you can quickly get into “diminishing returns,” without even considering any number of mechanical considerations.

Bill

* This is one of the reasons why trying to compare two binos with the same aperture, magnification, and nearly the same quality is senseless—it’s kinda like trying to ice skate UPHILL! There are just TOO MANY VARIABLES. And although much has been written about the differences in coatings, it’s just not so—observably so, anyway.

Sure there are differences. But trying to evaluate coatings for companies of similar experience in optics, is like trying to split hairs with an axe. Baffling, blackening, absorption of light by the glass in the elements, size and position of the field stop, knife-edge on the field stop, and other considerations take a toll. It’s like the 5th engine on a 747 (the APU). Just because most people are not familiar with it doesn’t mean it doesn’t exist.

WJC · Jan 16, 2015

Troubador said:
Bill

Wild Bill

In many ways you are right from a technical evaluation stand-point. However as packages of bundles of capabilities and characteristics, available to purchase at a given price, buyers do make comparisons that are valid on a personal level even if they are along semi-subjective lines.

Thus some comparisons that people are faced with before they buy might include: do I prefer the fast focus on this model or the flat field of this other one, at these prices? Or do I want the extra brightness of this one or the lighter weight of the other?

These are all valid personal buying choices just like deciding whether I would prefer to eat a banana just now or an orange :-O

Lee

Hi Lee:

I certainly agree. Key words being: "given price," "personal level," "semi-subjective," "fast focus," etc.

I most certainly do not make my buying decisions on clinical data. I just want folks to consider that it's there.

Cheers, wild Bill

Inquisitor · Jan 17, 2015

WJC said:
:The attached photo illustrates how this works. At a distance of 1 foot, a light source has a brightness of X, but when the distance is only doubled, the brightness is only ¼ X. Thus, it is easy to see how you can quickly get into “diminishing returns,” without even considering any number of mechanical considerations.

Unsurprisingly, this is exactly how it works with radiation sources..."double the distance, quarter the dose."

OPTIC_NUT · Jan 18, 2015

A dynamic analysis:

---the wider field lets in more total light
---this closes down your iris more
---as a result, each detail is less bright, actually

This only happens when it's bright, though, not dim.
So.....it doesn't matter much.

I think one reason that I prefer about 8 degrees, at
7x or 8x, is that the optic cortex doesn't have too much distraction,
can process things faster and easier. You really only pay close
attention to things near the center field where acuity is much higher.
Don't forget the cognitive psychology of the picture.

WJC · Jan 19, 2015

Inquisitor said:
Unsurprisingly, this is exactly how it works with radiation sources..."double the distance, quarter the dose."

But then, isn't LIGHT radiation? :t:

Bill

Troubador · Jan 19, 2015

WJC said:
But then, isn't LIGHT radiation? :t:

Bill

Wild Bill

But then, wasn't that Inquisitor's point? :t:

Lee

WJC · Jan 19, 2015

Troubador said:
Wild Bill

But then, wasn't that Inquisitor's point? :t:

Lee

Possibly! However, I thought he was speaking of a SPECIFIC type of radiation--as in THE INCREDIBLE HULK! Not to be confused with Catherine Bell, Catherine Zeta-Jones, or Charlize Theron who are now auditioning for the title role in the summer blockbuster . . . The Incredible HUNK!

Bill

Are Wide Angle Bins Brighter? (1 Viewer)

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