What is more important transmission or exit pupil size as we age? (1 Viewer)

[Maljunulo]

I don't see how the "resolution" of a binocular varies with type of support.

That is determined by physics and the manufacturer.

 

[Jessie-66]

EdZ has probably used test panels (USAF1951?) to investigate how resolutions (imho without booster) differ with binoculars of different magnification and support. It was just a memory, an initial thought, a long time ago that I read the thread.
I know that the human eye can resolve 1 angular minute under ideal conditions. Our hand-held binoculars with low magnification are far better, you need booster for tests of bins. The human eyes are otherwise the "bottleneck".

 

[Maljunulo]

I think that was my point, or part of it.

Irrespective of how well we see the resolution chart, the resolution of the binocular does not change.

Perhaps he called it something like "effective resolution" or "apparent resolution".

 

[Jessie-66]

I found the thread, posts #58 and #62.
How useful it is in terms of topic, I don't know yet. For now, for the "records".

Binocular Resolution Testing w/USAF Charts - Page 3 - Binoculars - Cloudy Nights

Page 3 of 4 - Binocular Resolution Testing w/USAF Charts - posted in Binoculars: When testing the central vision of an eye we use a 10 deg field. This is measured from the center of fixation. This results in a 20 deg edge to edge field. Photopic acuity drops off rapidly after that. There is a...

www.cloudynights.com

A long time ago I read a scientific paper (student research project or diploma thesis) comparing Zeiss 20x60S versus Canon IS, including measurements. I have not (yet) found the paper.

 

[jring]

Both quantities are overrated and their importance for "twilight viewing" is exaggerated. Here is why

a- Human eye does not perceive brightness proportional to the area of the eye pupil. This is due to an effect known as Stiles–Crawford effect of the first kind. The graph below shows the relative sensitivity of the cone receptors of human eye as the pencil of light entering the pupil gets larger. As you can see, the light that enters near the edges of eye pupil is much less effective in creating "perceived brightness".

Hi Omid,

thanks for your interesting post which I mostly agree with - except for point a).

At least the german wikipedia arcticle on the Stiles-Crawford effect (both kinds) states that it only occurs in daylight due to the fact that it is caused by the structure and distribution of the cones. The english article is not quite as clear but also mentions that it is much reduced under scotopic conditions and goes on to explain it again with structure and distribution of cones...

I am not really convinced that we can use it to explain what influences scotopic vision...

Joachim

 

[Gijs van Ginkel]

This topic circles around the differences in brightness between different binoculars and the properties determining it . In "Die Fernrohre und Entfernungsmesser" by Albert König und Horst Köhler, Springer Verlag, 1959, the authors make it perfectly clear that the optical properties in the sense of the amount of light passing an optical system like binoculars and telescopes is determined by two factors only: the size of the exit pupil and the amount of light the optical system transmits.
But now another phenomenon is discussed : brightness. However, brightness is not only determined by the light intensity the eye is exposed to. The color hue also plays a role in our perception of brightness. Our brain judges yellow for example as a bright color, whereas that is not so for violet.
So the answer to the question Denis formulates in post 20 can not be answered straightforward, since the shape of the transmission spectrum does play a role here since it reveals information about the color distribution of the transmitted light and the overall color hue of that light.
Gijs van Ginkel

 

[Jessie-66]

Hello Gijs, please say something about contrast perception in twilight and residual light. In twilight we still perceive colours, in moonlight only contrasts. What interests me in particular: From your scientific point of view, does it make sense to analyse the data from EdZ and mathematically reduce the resolution gain according to Köhler and Leinhaus for hand-held binoculars, so that one has a comparison with IS binoculars? The ideal case (tripod or perfect image stabilisation) would imho be the resolution gain according to Köhler and Leinhaus, real and not ideally functioning IS is probably comparable to binoculars supported by elbows. I know that a result would only be valid for the user EdZ under his observation conditions (good lighting, black and white contrasts of the test chart etc.). But better than nothing, for a comparison/forecast from IS- and non-IS-bins one would have "something in hand". With more data from others, my idea could be improved. I am an engineer (planner) and not a scientist or researcher, I only apply their results practically as correct as possible.
@Omid: I am also interested in your reasoned view.
Best regards. Jessie

 

[Troubador]

Hi Omid,

thanks for your interesting post which I mostly agree with - except for point a).

At least the german wikipedia arcticle on the Stiles-Crawford effect (both kinds) states that it only occurs in daylight due to the fact that it is caused by the structure and distribution of the cones. The english article is not quite as clear but also mentions that it is much reduced under scotopic conditions and goes on to explain it again with structure and distribution of cones...

I am not really convinced that we can use it to explain what influences scotopic vision...

Joachim

And there is the phenomenon in darkness of how 'averted' vision using the edge of the eye's field of view can be more effective at using the light from faint sources.

Lee

 

[Sterngucker]

And there is the phenomenon in darkness of how 'averted' vision using the edge of the eye's field of view can be more effective at using the light from faint sources.

Lee

Especially intriguing considering the Stiles-Crawford Effect (SCE1) explained by Omid, where the perception of brightness decreases towards the temporal and nasal sides because of the angle of reception of the rods which are placed on the wall of what for our purposes is a sphere (presumably all 'pointing' inwards, possibly to some sort of 'focal point').

 

[Binastro]

Averted vision can be very powerful with up to 30 times gain at 20 degrees from central vision at night.
Much less in twilight.

It varies person to person and left or right, up or down.
An angle is found that is best for the individual.

It varies for point sources and extended sources and the size of the source.

There is also the tapping or rocking of a telescope to introduce movement.
So having a stationary binocular is not always best.

It takes skill and practice to get the best benefit.

Then there is dark adaptation that has an enormous effect.
This is a chemical effect taking 20 minutes to hours or days to achieve the full gain.
Older people lose a lot of this ability.

Then there is yellowing of the eye, cataracts etc.

So 'theory' only goes so far, and does not necessarily reflect reality.

Regards,
B.

 

[Jessie-66]

But now we have arrived at another topic, not that of the OP. Up to now, we have been dealing with the detection of not self-luminous objects. The models considered so far (target detection) are not designed for (point) light sources, stars. Just for the record.
I find the "digression" interesting - but we need now other mathematical models, formulas for astronomers with hand-held bins and telescopes with big objectives and high magnification and can not more use the formulas and diagrams for birdwatcher (owl detection), hunters and soldiers in twilight and moonlight.

 

[Binastro]

Post #90 refers to unaided eyes, binoculars of all sizes and telescopes.

It also applies to things like owls and buzzards in dark or semidark skies.

It matters not if one is looking for M33, a faint galaxy, or a dimly lit owl.

Self luminous or reflected light. It is the same.

B.

 

[Omid]

Hi Omid,

thanks for your interesting post which I mostly agree with - except for point a).

At least the german wikipedia arcticle on the Stiles-Crawford effect (both kinds) states that it only occurs in daylight due to the fact that it is caused by the structure and distribution of the cones. The english article is not quite as clear but also mentions that it is much reduced under scotopic conditions and goes on to explain it again with structure and distribution of cones...

I am not really convinced that we can use it to explain what influences scotopic vision...

Joachim

Hello Jiring,

Thank you for your interest. You asked an excellent question.

First, please note that my original Post #14 was about twilight viewing (mesopic vision) not night viewing (scotopic vision). See the diagram below.

Second, note that Wikipedia says that SCE-1 (Stiles-Crawford Effect - Type I) is "most evident under photopic conditions" which is correct but somewhat misleading: Reading this, one might think that Stiles-Crawford Effect "only occurs at daylight" which would be incorrect. SCE-1 is - as far as known today- is due to waveguide-like characteristics of cones. So, as long as your vision is mediated by cones, the SCE-1 effect is at work.

Third, note that when you look at anything during twilight/low-light, your vision is still mediated by cones. When we "look at something", we are using our foveal vision which is mediated by cones. There are no rods in the fovea. Furthermore, anytime you see color, such as when seeing colorful stars at night, this indicate vision by the cones.

Therefore, when you pick up your binoculars to look at an owl sitting on a three in twilight, your vision is still mediated by cones and your perceived brightness is affected by the SCE-1.

Scotopic vision -mediated by rods in the retina- is primarily a "surround vision" sense. It provides us with the extremely important - to our hunter ancestors not to us Amazon Prime shoppers- ability to maintain an upright body posture and walk in the dark. Surround vision helps the brain pick up the horizon line and other significant features of the terrain that are necessary for proprioception which is the sense of self-movement and body position. When it gets so dark that cones cease to function, the ability to focus on an object using frontal vision is lost but the ability to maintain posture and walk in the dark is maintained. Under scotopic conditions, we are literally blind in the center of our gaze. Our visual system fills this gap with information from the surrounding retinal regions (which do contain rods) so we "think" we see things at the center of our vision while, in truth, we don't.

Stated simply, under scotopic conditions we can still "see our environment" but we cannot "look at specific objects".

Sincerely,
-Omid

 

[Maljunulo]

Being somewhat simple-minded and practical, when I can't tell if the subject is in focus, I give up and go home.

 

[Gijs van Ginkel]

Since I am an experimentalist, I had the following considerations:

• Contrast means that an object can be distinguished from its background
• At low light levels our vision is governed by black and white vision triggered by the cones in our eyes.
• When I now take two binoculars: an 8x42 and a 12x42 with exactly the same transmission spectra, the effect of the 12x is that the image comes closer but since the exit pupil is smaller less light reaches the eye.
• If I now perform an experiment at a very low light level looking at an object at a low contrast background, I can not distinguish the object clearly from the background (8x binocular), but when I come closer (12x binocular) the object can be better separated from its background because of a higher observed contrast.

Gijs van Ginkel

 

[Binastro]

Omid nice diagram post #93.

I was outside the observatory on the mountain in Tenerife.
It was cloudy.
It was so dark, despite my very good dark vision, I could see nothing at all.

I walked around and just by luck I missed falling into the caldera by maybe two metres.
The ground I was walking on was invisible.

It is possible if I had been very dark adapted, say half an hour plus, I might have seen something.
That is the darkest I have seen outside, although during an extensive power cut in England I could see nothing at all at home at night.

If the stars are out there is enough light to see something.

In 1952 the smog was so intense I could not see my feet.
I got home by feeling the walls on my street.
When I got home I rang the bell.
Wrong house.
Two doors down from my house.

The Clean Air Act was brought in after that.
Regards,
B.

 

[tenex]

In 1952 the smog was so intense I could not see my feet.

Wow. I tend to associate "pea soup" like that with Victorian London. Was so much coal still being burned in 1952?

Thank you for your interest. You asked an excellent question.

(already asked by me in post #79)

First, please note that my original Post #14 was about twilight viewing (mesopic vision) not night viewing (scotopic vision).

Yes, a good clarification, this thread concerns mesoptic vision not scotopic. But as Gijs reminds us and Holger states in his paper referenced above, "In real life, target detection under low light is rarely resolution, but rather contrast limited."

when you pick up your binoculars to look at an owl sitting on a three in twilight, your vision is still mediated by cones and your perceived brightness is affected by the SCE-1.

"Perceived brightness" of a scene involves more than the fovea, so we need to be more precise than this about what's going on here. If you want to resolve fine detail on an owl in twilight, it's possible that the advantage of large objectives is reduced by SCE-1, though you've cited no studies to confirm by how much. If you want to find the owl in the first place (and the previous question becomes irrelevant if you can't), the advantage of large objectives remains clear, exactly as usually stated. I'm still going to be carrying my 10x56.

 

[Sterngucker]

...

"Perceived brightness" of a scene involves more than the fovea, so we need to be more precise than this about what's going on here. If you want to resolve fine detail on an owl in twilight, it's possible that the advantage of large objectives is reduced by SCE-1, though you've cited no studies to confirm by how much. If you want to find the owl in the first place (and the previous question becomes irrelevant if you can't), the advantage of large objectives remains clear, exactly as usually stated. I'm still going to be carrying my 10x56.

Exactly.

 

[[email protected]]

Hello Jiring,

Thank you for your interest. You asked an excellent question.

First, please note that my original Post #14 was about twilight viewing (mesopic vision) not night viewing (scotopic vision). See the diagram below.

Second, note that Wikipedia says that SCE-1 (Stiles-Crawford Effect - Type I) is "most evident under photopic conditions" which is correct but somewhat misleading: Reading this, one might think that Stiles-Crawford Effect "only occurs at daylight" which would be incorrect. SCE-1 is - as far as known today- is due to waveguide-like characteristics of cones. So, as long as your vision is mediated by cones, the SCE-1 effect is at work.

Third, note that when you look at anything during twilight/low-light, your vision is still mediated by cones. When we "look at something", we are using our foveal vision which is mediated by cones. There are no rods in the fovea. Furthermore, anytime you see color, such as when seeing colorful stars at night, this indicate vision by the cones.

Therefore, when you pick up your binoculars to look at an owl sitting on a three in twilight, your vision is still mediated by cones and your perceived brightness is affected by the SCE-1.

Scotopic vision -mediated by rods in the retina- is primarily a "surround vision" sense. It provides us with the extremely important - to our hunter ancestors not to us Amazon Prime shoppers- ability to maintain an upright body posture and walk in the dark. Surround vision helps the brain pick up the horizon line and other significant features of the terrain that are necessary for proprioception which is the sense of self-movement and body position. When it gets so dark that cones cease to function, the ability to focus on an object using frontal vision is lost but the ability to maintain posture and walk in the dark is maintained. Under scotopic conditions, we are literally blind in the center of our gaze. Our visual system fills this gap with information from the surrounding retinal regions (which do contain rods) so we "think" we see things at the center of our vision while, in truth, we don't.

Stated simply, under scotopic conditions we can still "see our environment" but we cannot "look at specific objects".

Sincerely,
-Omid

View attachment 1360185

Nice diagram and explanation of Scotopic Vision. Interesting how complex vision really is!

 

[[email protected]]

Omid nice diagram post #93.

I was outside the observatory on the mountain in Tenerife.
It was cloudy.
It was so dark, despite my very good dark vision, I could see nothing at all.

I walked around and just by luck I missed falling into the caldera by maybe two metres.
The ground I was walking on was invisible.

It is possible if I had been very dark adapted, say half an hour plus, I might have seen something.
That is the darkest I have seen outside, although during an extensive power cut in England I could see nothing at all at home at night.

If the stars are out there is enough light to see something.

In 1952 the smog was so intense I could not see my feet.
I got home by feeling the walls on my street.
When I got home I rang the bell.
Wrong house.
Two doors down from my house.

The Clean Air Act was brought in after that.
Regards,
B.

How is the smog in the UK now? Is it better than New York or big cities in the US?