Just Curious: Does FOV Influence Brightness? (1 Viewer)

WJC said:

Hi Ed:

I couldn't either; that's why I'm on the diabetic diet.

Although, the diabetic diet is extremely simple. All you have to remember is:

IF IT TASTES GOOD . . . YOU CAN'T HAVE IT! :C

Bill

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So I don't eat the first chocolate chip cookie.

My friend, I'm HERE TO SAVE YOU! If you haven't heard of the LCHF way of eating, then you must look into it. I've been diabetic since 1980, taking meds and doing what the white coated robots insisted upon (except for taking statins). So it's been a long time.

About two months ago I switched to LCHF based on my daughter's recommendation. Wow! I lost 10 lbs very quickly (she lost 45) and now I have no more need for diabetes medications. My average H1c has settled down to 6.2-6.5, which isn't all that bad for a diabetic. I don't miss the bread, potatoes, pancakes, rice and breakfast foods as much as I enjoy the delicious bacon, eggs, cheese, fatty chicken, pork tenderloin, vegetables, whole milk, and protein drinks — to name a few.

What does this all have to do with binoculars? Well, for starters, diabetic retinopathy ain't so good for the view. Enough said, we can discuss it more on PMs or email.

Help is on the way (or at least an opinion). :t:

Ed

elkcub said:

Hi Holger,

On second thought I'm having a hard time following the reasoning for: "This may imply that a narrow angle binocular is perceived a little bit brighter than a wide angle binocular of identical transmission. During daytime, that is." Assuming equal transmission, if the the eye contracts more to a wider adapting field, where is the implication that a smaller field might seem brighter?

Ed

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Hi Ed,

Me too, I am not sure about that. I just imagine a situation similar to a running TV during the night: If the room is dark, the TV screen appears bright, too bright at times, and once you switch on the room light, it is OK. A binocular with tunnel view has a rather narrow, bright spot, and lots of black area around, which then makes the image appear brighter than it would through a wide angle binocular. Frankly, I never tested that systematically.

Cheers,
Holger

elkcub said:

Hi Holger,

On second thought I'm having a hard time following the reasoning for: "This may imply that a narrow angle binocular is perceived a little bit brighter than a wide angle binocular of identical transmission. During daytime, that is." Assuming equal transmission, if the the eye contracts more to a wider adapting field, where is the implication that a smaller field might seem brighter?

Ed

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Holger Merlitz said:

Hi Ed,

Me too, I am not sure about that. I just imagine a situation similar to a running TV during the night: If the room is dark, the TV screen appears bright, too bright at times, and once you switch on the room light, it is OK. A binocular with tunnel view has a rather narrow, bright spot, and lots of black area around, which then makes the image appear brighter than it would through a wide angle binocular. Frankly, I never tested that systematically.

Cheers,
Holger

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Hi Ed, Holger,

Apart from the apparent increase in contrast between a narrow source (field) and the black surround, are these pupil reponses subject to a typical sinusoidal control curve - ie. the brightness aperture is first overshot, then that overshoot over corrected, etc, in a decaying amplitude toward the equilibrium point?

My immediate thought to the OP's initial question was yes, it does matter, thinking that even though the per unit flux was the same, that the integral over the Fov would surely come into play. If the pupil self regulates as Ed mentioned in the quote below, then I believe that the "apparent" brightness would be greater since the comparison, even though between similar steady state brightness levels, would come down to a stopped down, lower aberration view v's a dilated, higher aberration one.

Really, I'm still trying to "digest" Ed's earlier remark about the pupil - "Secondarily, in synchrony with light adaptation, it seeks a resting aperture that balances diffraction effects while minimizing internal aberrations." :brains: .... it seems like there more than one head honcho in this noggin' of mine!


Chosun :gh:


PS. Ed, have you researched Low GI? (carbs, generally unprocessed wholegrain types) .... this quasi paleo stuff has a place, but the high levels of consumption of saturated animal fats is a 'cure' that outweighs the 'disease'. It too is "unnatural" --- unless of course you spend the morning running down the beastie, before becoming involved in a fight to the death with it, before putting a well aimed spear through it and then carting half the carcass back to the waiting family ! ..... just a thought! :h?:

Chosun Juan said:

Apart from the apparent increase in contrast between a narrow source (field) and the black surround, are these pupil reponses subject to a typical sinusoidal control curve - ie. the brightness aperture is first overshot, then that overshoot over corrected, etc, in a decaying amplitude toward the equilibrium point?

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Hi Chosun,

I leave answering your other questions to others but as a former student of one of the most renowned control theory professors , let me answer this one!

The eye's response to brightness is slow (= over damped control system). It does not over shoot. You can easily test this: if you move from a very bright room to a dark room, you won't see any thing for many seconds. Similarly, when you walk out of a dark movie theater, it takes many seconds or even minutes till your eyes can adjust to normal daylight.

I experience pupil bounce and have done for years, where the pupil size oscillates.

Part of the response you mention, Omid, is due to chemical changes, not pupil size changes.

Now my pupil responses seem slower due to age.

As I generally don't get much sunshine, although I need it, my eyes don't like bright sunshine any more, and I shield my eyes.
This may be partly because of eye defects, although my optician says I have no need for cataract treatment.
But I think that the level of light a person is used to creates long term changes and it may take time, days or weeks to adjust.

I take vitamin D, but this is not fully effective I think, and I should get more sunshine.
As a daily H alpha and white light solar observer, who has been recording hundreds of protected unaided sunspots for decades I am ultra careful over eye safety.

P.S.
I still could just see the remnants of the enormous sunspot with protected unided eyes that I first spotted maybe ten days ago.
It was very close to the limb and I estimated it as about 45 arc seconds penumbral size.
When I first saw it I estimated it as 70 arc seconds growing to over 90 arcseconds.
This was I think the largest sunspot since 2001?

Holger Merlitz said:

Hi Ed,

Me too, I am not sure about that. I just imagine a situation similar to a running TV during the night: If the room is dark, the TV screen appears bright, too bright at times, and once you switch on the room light, it is OK. A binocular with tunnel view has a rather narrow, bright spot, and lots of black area around, which then makes the image appear brighter than it would through a wide angle binocular. Frankly, I never tested that systematically.

Cheers,
Holger

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Sorry for jumping over a few other posts, but we're thinking along the same lines (I think), namely
Brightness Constancy and Simultaneous Brightness Contrast. (Similar material appears in several texts, but this link doesn't violate any copyrights.) As summarized by Professor Heeger, "simultaneous brightness contrast" is an illusion (i.e., a percept inconsistent with physical reality), but it is consistent with the way the retina goes about establishing brightness constancy (i.e., maintaining constant brightness percepts under changing viewing conditions).

We don't have a simultaneous brightness contrast situation when looking through narrow field binoculars, because there is only one field. It comes closer to the left side of the Koffka Ring Illusion (panel 2). However, as you said, the black annulus established by the field stop produces an unusually high contrast ratio relative to normal vision, and probably leads to the perception/illusion of a brighter viewing field. This makes sense to me, because when the same narrow field binoculars are used with eyeglasses their apparent brightness tends to disappear, which I assume is because the contrast ratio is reduced.

In general, the same effect obtains with eye shields that eliminate peripheral stimulation and restrict the view to only what's contained within the field stop limits. (I'm leaving out the stray light issue, which also reduces contrast.)

Cheers,
Ed

Ed, your link is not working for me??

I still can't help but think that a wider Fov does increase brightness due to the greater overall integral of light. Normally (most daytime viewing) the pupil adjusts (apparently self-regulating! .... must have a word to those cheeky pupils |8.| - I thought I was the boss around here! :brains: to cancel out this greater amount of light. However, once the environmental light levels drop, so that the pupil diameter dilates to a greater size than the exit pupil, then wouldn't that greater Fov deliver a brighter image to the exit pupil size constrained eye? I am thinking this comes into play, particularly noticeable for the ~4mm EP size (8x32, 10x42, 12x50, etc), but equally applicable to greater EP sizes (ie. 5mm+) as the light levels drop. I am figuring that this is of more importance to younger folk, whose pupils dilate to greater sizes.

A 120m Fov 10x42 takes in a viewing area ~ 20% greater than a 110m Fov 10x42. How much brighter will the image of the 120m Fov bin be once light levels drop so that the pupil dilates to greater than the 4.2mm EP size?


Chosun :gh:

Hi Chosun,

I think the link is fixed now. Give it a try and we can pick up the conversation in that context, ... and also limit ourselves to photopic situations were the pupil is equal or smaller than the XP of the binoculars.

Ed

PS. I'll be away from my computer for the next day or two.