• BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

    Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

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

[email protected]

Well-known member
Supporter
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
"The color hue also plays a role in our perception of brightness.'

What colors hues do we perceive as the brightest?
 

[email protected]

Well-known member
Supporter
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.
Interesting that averted vision could give you that much benefit in seeing things. Do you mean that when you get older your eyes have very little adaptation to the darkness versus when you are younger? So basically if you are older stay home when it gets dark or have a good torch.
 

Jessie-66

Germany
Hi Troubador, I have an interesting thread (PNs) with a man, who has a red-green visual impairment. He says 1 in 12 men have it, women much less often. Perceived color cast (green, blue) with Zeiss and Swarovski, not with Leica. Current status of the discussion: Some transmission curves obviously filter at the blue/violett part of the spectrum (Leica, Meopta). Others (Zeiss, Swaro) are relatively "flat". 2 filters in serie/superposition (binoculars transmission curve + eyes transmission curve with color weakness) can amplify or balance color cast. Correlations to the perceived color cast seem likely to me, but in everyday life (without binoculars) the brain corrects a lot in long time observations and hardly comprehensible for scientists: Changes in the color temperature of LED displays (TV) are often no longer perceived after a few minutes, brain adapts color perception.
Filtering (low values of the transmission curve) leads to increased perception at the "other end" of the spectrum, opposite colors of the color wheel. Simplified but vividly expressed. I am not a scientist only practitioner. ;-)
I have suggested targeted tests with diverse bins and different observation situations but delayed through pandemic, mutations of virus, and related tightened measures.
I don't think mild visual impairments regarding color perception are often recognized/diagnosed: Gijs wrote of frequent yellowing of the eye lenses of older people (= 2 different color filters in overlying formation / "series connection", bins + eye lenses), increased perception in the blue/violett range of the spectrum / color wheel). I see correlations to color casts. One should give the binoculars with alleged color cast to wife, daughter or young humans for examination.
Thesis: With Leica (or Meopta) transmission and blue/violet filtering transmission curves humans with red-green color weakness achieve an overall more uniform (relatively flat) but slightly lower overall transmission curve (bins + eyes). My dialog partner says so far that he perceives less detail with Leica bins but without color cast. Maybe these humans do need the blue/violett part of the spectrum for details (individual adaptation/adjustment of the brain for compensation of color weakness) more as normal sighted people and have to accept the green or blue color cast for that. Specific tests to compare detail recognition with Leica-, Zeiss- and Swaro bins with color different observation objects, ambient light, twilight, dust, short and longer observation times are delayed. Perhaps my dialogue partner can after tests select the appropriate binoculars with a special transmission curve for different observation situations. Multiple, differently pronounced color weaknesses I would not like to assess, individual targeted testing should be useful.
Merry Christmas for you, Troubadoris, my dialog partner and all readers. Jessie

edit: Text extended and corrected.
 
Last edited:

Troubador

Moderator
Staff member
Supporter
Hi Troubador, I have a interesting thread (PNs) with a man, who has a red-green visual impairment. He says 1 in 8 men have it, women much less often. Perceived color cast (green, blue) with Zeiss and Swarovski, not with Leica. Current status of the discussion: Some transmission curves obviously filter at the "blue/violett end" of the spectrum (Leica, Meopta) others are relatively "flat" (Zeiss, Swarovski). 2 filters in series (binoculars transmission curve + eyes transmission curve with color weakness) can amplify or balance color cast. Correlations to the perceived color cast seem likely to me, but in everyday life (without binoculars) the brain corrects a lot in long time observations and hardly comprehensible for scientists: Changes in the color temperature of LED displays (TV) are often no longer perceived after a few minutes.
Filtering (low values of the transmission curve) leads to increased perception at the "other end" of the spectrum, opposite colors of the color wheel. Simplified but vividly expressed. I am not a scientist only practitioner. ;-)
I have suggested targeted tests with diverse bins but delayed through pandemic, mutations in the virus, and related tightened measures.
I don't think mild visual impairments regarding color perception are often recognized/diagnosed. Gijs spoke of frequent yellowing of the eye lenses of older people (= 2 color filter in series connecton, bins + eye lenses), increased perception in the blue/violett range of the spectrum / color wheel). I see correlations to color casts. One should give the binoculars with alleged color cast to the wife or daughter or young humans for examination.
Thesis: With Leica and Meopta transmission, blue/violet filtering transmission curves humans with red color weakness achieve an overall uniform (relatively flat) but slightly lower overall transmission curve. Multiple color weaknesses I would not like to assess, individual targeted testing should be useful.
Merry Christmas for you and all readers. Jessie
It is a fascinating topic. No wonder it is hard for members to agree on the colour balances of binos.

Lee
 

Binastro

Well-known member
Hi tenex,

Post #97.
Yes, we only burned coal.
The coal man delivered 20 sacks of one hundredweight, which we stored in a shed near the kitchen.

After the great smog, which killed over 10,000 people and caused illness in over 100,000 the coal was replaced by coke. Not cola, but a substance with some of the deadly stuff removed.

As a school trip we went to a gas works, and I was so fascinated I wanted to work there when I grew up, They made, from memory, about 1500 things from coal.

The pea soupers were common, but the great smog was extreme. I think the most extreme event in British history.

There was a problem also with tuberculosis, and we had mass mobile x-ray units coming to our streets.
I think they used the Wray 64mm f/0.71 lenses designed by Wynne in 1951.
He actually said it was quite easy to design, but they used thorium glass.
I thought that 16mm film was used, but I am told it was 35mm film.

Regards,
B.
 

Binastro

Well-known member
Hi,
Post #100

The air quality in the U.K. is good nowadays.
I do not think we have smog any more, bit it is rare to get really transparent skies in town.
The best conditions are after rain and especially during gales coming in from the north of the North Sea.

In the 1980s I could see M33 standing under a lit street light in Margate without optical aid.
This was even better than in Finland, where the air was very clean indeed.

I haven't been to the U.S. since 1989, so I don't know how things compare nowadays.

Arosa in Switzerland had remarkably clean air on a visit in the 1960s. at 10,000ft altitude.

At 37,000ft above the Atlantic in a Boeing 747 at night from the cockpit stars were seen down to the horizon without optical aid.
The tail wind was 100 mph.
The cockpit windows were very good with a 10x25 binocular despite being very thick.
Passenger windows were poor.

Regards,
B.
 

Binastro

Well-known member
Hi,
Post #102.

I can only speak personally, but dark adaptation is much slower and less deep when older.

I think, though, that is common as we age.

Regards,
B.
 

[email protected]

Well-known member
Supporter
Hi tenex,

Post #97.
Yes, we only burned coal.
The coal man delivered 20 sacks of one hundredweight, which we stored in a shed near the kitchen.

After the great smog, which killed over 10,000 people and caused illness in over 100,000 the coal was replaced by coke. Not cola, but a substance with some of the deadly stuff removed.

As a school trip we went to a gas works, and I was so fascinated I wanted to work there when I grew up, They made, from memory, about 1500 things from coal.

The pea soupers were common, but the great smog was extreme. I think the most extreme event in British history.

There was a problem also with tuberculosis, and we had mass mobile x-ray units coming to our streets.
I think they used the Wray 64mm f/0.71 lenses designed by Wynne in 1951.
He actually said it was quite easy to design, but they used thorium glass.
I thought that 16mm film was used, but I am told it was 35mm film.

Regards,
B.
That reminds when incinerators were used in the US to burn your trash. Everybody had one in their backyard until they were declared illegal.
 

[email protected]

Well-known member
Supporter
Hi,
Post #102.

I can only speak personally, but dark adaptation is much slower and less deep when older.

I think, though, that is common as we age.

Regards,
B.
It does get harder to drive at night as you age. That is why when I buy a new binocular I really consider exit pupil and transmission. Compacts are great for their portability but with their small exit pupils they are more for the younger set.
 

Troubador

Moderator
Staff member
Supporter
I bet that is why Zeiss have the green cast. Zeiss binoculars in general appear very bright to me, but they also have high transmission.
Dennis allow me to gently correct you by suggesting what you meant to post was 'I bet this is why some people see a green cast in Zeiss binos'. My theory is that Zeiss T* coating is very efficient at transmitting light in the yellow-green and that people who are more sensitive than average to this light perceive this as a colour cast whereas people with average sensitivity don't. This is of course only a theory.

Lee
 

Gijs van Ginkel

Well-known member
Lee, post 113,
I support your theory, the Zeiss spectra show a very shallow and broad increase of transmission in the green yellow part of the spectrum without generating a color cast, see the spectrum of the Victory SF 8x32.
Gijs van Ginkel
 

henry link

Well-known member
I guess I'll pull out this old post one more time:


The image was assembled by cropping and arranging in Powerpoint five photos; one a straight shot of a white piece of paper in sunlight and the other four taken backwards through four binoculars set up between the paper and the camera. Does anybody notice a color bias in the transmission of any of the binoculars?
 
Last edited:

henry link

Well-known member
I guess I should have narrowed the question. Forget all the small squares except the one on the upper right. If we accept the background color as neutral, what color is that square?
 

Binastro

Well-known member
Small square top right slightly green.

But big square hint of blue.

However, for my observations I wouldn't call them colours.

My computer screen may not be neutral.

Regards,
B.
 

Patudo

Well-known member
For what it's worth, I perceive (on my monitor) all four small squares in Henry's slide1.jpg as shades of grey, with maybe a very slight hint of green in the top right square. The bottom right square seems the darkest grey to me (lowest light transmission?).

I can honestly say I didn't realize the extent to which each of us sees things differently (and indeed the differences in how even my left and right eye see colour) until I read some of the threads here on Birdforum. As the song goes - we have just one world, but we live in different ones...

After spending several late afternoons/evenings the last few weeks observing a pair of peregrines that seem to be keen on hunting very late (the last kill I recorded, on Monday, was taken at 16.06, just over ten minutes after official sunset), I feel the ideal low light binocular should have both high transmission and a large exit pupil, the latter as much for its easier eye placement (which helps with steadiness) as for increasing the light available to the eye. The effects of shake/wobble seem greater in poor light - when comparing binoculars used unsupported to braced against a convenient structure at these times I have noticed a striking improvement in what I could see - and larger exit pupils seem steadier to me even if magnification is the same. Image stabilization, of course, also steadies the image. I'm sure something like the 10x56 SLC would perform better under those conditions than the 10x42 SE I've been using (assuming I could keep the big unit steady). But after reading kabsetz's comments in the thread I linked to in my last post on this thread, it wouldn't surprise me that the 10x42 IS, though not as bright, might be better for actual observation until it got really dark.
 

A2GG

Beth
Supporter
United States
Dennis allow me to gently correct you by suggesting what you meant to post was 'I bet this is why some people see a green cast in Zeiss binos'. My theory is that Zeiss T* coating is very efficient at transmitting light in the yellow-green and that people who are more sensitive than average to this light perceive this as a colour cast whereas people with average sensitivity don't. This is of course only a theory.

Lee
When I had the FL 8x32 I noticed greens would pop a little bit. It wasn't a 'color cast' per se, but just an emphasis when looking at Pine trees and other greenery. I agree some people may notice this and others won't.

I've been thinking about colors a lot lately and this is due to the Nikon MHG having an obvious (to me) bias towards yellow. I noticed this initially when comparing it to the CL 8x30 which has a more color neutral image. As I began using the Nikon solely over the next several weeks the colors began to look more neutral since I wasn't comparing it anymore. However, this past weekend I finally noticed the color bias in the MHG on its own, in certain light conditions, while out birding; it just came to me without looking for it. I don't mind this at all and actually really like its distinct color tones and image quality.

While shopping for bowls and plates recently I became a bit obsessed with white dinnerware and the different shades of white. I noticed this when comparing bone china bowls and plates to regular porcelain. The bone china looked a pure white, while the white porcelain ranged from cold to warm compared to the 'true' white of the bone china dishes; some porcelain bowls looked a touch blue-gray (cold) in comparison while other pieces had a slight touch of yellow (warm) next to the bone china. The warmish toned ones looked like a creamy off-white with just a hint of subtle yellow. One of the warmer white dishes were described as 'crisp white' in the AD blurb, but they really aren't when compared to the bone china pieces.
If you did not compare these pieces with the clean/true white bone china, you would see them as just white dishes and you may not be able to see their inherent slight warm/cold tones. When looking through your binocular whites will just look white until you compare them with other bins; then you may be able to see the difference. The more neutral binos should show striking pure whites just as the Swaro CL does. I always really liked the colors in the CL, but I also find the warmish binos very relaxing and pleasing too; Ultravid, Monarch HG, Meostar all have a slight warmish image IMO. I noticed the Cabela's Euro HD had a slight hint of yellow when comparing it to my old Ultravid Plus several years ago.

I agree with Holger who mentioned in one of his reviews that a slight yellow or warm bias is just fine in binoculars since they can provide a relaxing image which can help to reduce eye strain. I'd probably have difficulty finding the review where he mentioned this and I'm not quoting him accurately, but the general thought was that a slight yellowish/warm bias can be beneficial for extended viewing.
 
Last edited:

Users who are viewing this thread

Top