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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Light Transmission in Binoculars (1 Viewer)

F

fotbg

Active member
Hi all,
Just wanted some clarification on the transmission of light through binoculars. My understanding is that transmission (%) is the amount of light that will pass through to your eyes. Glass quality, coatings, number of surfaces etc all play a factor.

My question is, will transmission be different for two given binoculars equally constructed the same, but with different magnifications and objective sizes?
For example - an 8x56 vs an 8x30 from the same manufacturer/line, lets say both Nikons for argument sake. Will the transmission value be better on the binocular with larger exit pupil?
 
Bins from the same manufacturer and line but of different sizes often have different numbers of lenses, so they can have different transmission. I find that all quality bins these days have superb transmission, so I don't consider the differences at all important even though, technically, they exist.

--AP
 
The things that affect transmission are the quality of the coatings on the glass, the number of air to glass surfaces, the quality of the glass with HT glass being used in some binoculars and the type of prism. AK and Porro prisms transmit better in general than SP prisms because they are more efficient so binoculars like the bigger Zeiss FL's with AK prisms are going to be better transmitters than binoculars with SP prisms. Porro prism binoculars transmit better because their prism is more efficient also and they have less air to glass surfaces in them than a comparable roof prism. Eyepiece design affects transmission also. If a binocular has simpler eyepiece design with less lenses in it it will transmit better because there is less air to glass surfaces. For, example, the Swarovski Habicht porro's are very high transmitter's because they have are porro's which are one of the most efficient prism designs with less air to glass surfaces, they have some of the best EL glass and the some of the best EL coatings. The 7x42 Habicht is one of the highest transmitting Habicht's because it has a simpler Kellner eyepiece with less lenses in it. A lot of your bigger aperture binoculars like the 8x56 like you mentioned are high transmitters because they have the room to use the bigger AK prism in them hence they will have higher transmission. Exit pupil really has nothing to do with transmission and transmission is more complicated than just magnification or aperture size. It depends on the total binocular design and the quality of the binocular. A good rule of thumb is a higher quality binocular will have higher transmission because of better quality coatings and glass and binoculars with AK prisms and Porro Prism binoculars will be higher transmitter's. Transmission makes a big difference and it is an advantage of the porro prism design and roof's with the AK prism. A really high transmitting binocular can make up for a smaller aperture in many cases.
 
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Alexis sez:
I find that all quality bins these days have superb transmission, so I don't consider the differences at all important even though, technically, they exist.

But then Dennis sez:
Transmission makes a big difference


hmmmmm... real world experience vs. quoting transmission percentages on a forum? I wonder.
:)

-Bill
 
wdc said:
Alexis sez:
I find that all quality bins these days have superb transmission, so I don't consider the differences at all important even though, technically, they exist.

But then Dennis sez:
Transmission makes a big difference


hmmmmm... real world experience vs. quoting transmission percentages on a forum? I wonder.
:)

-Bill
Click to expand...

It is amazing and frustrating to me how people want to blame everything related to binocular observing ON THE INSTRUMENT, with almost no regard for the different physiology between observers, where a HUGE part of the differences would come into play. It seems that some people think because THEY don't understand it, it doesn't exist.

"Stacking BBs all night long ... daylight come an me wan go home." :cat:

The other Bill
 
wdc said:
Alexis sez:
I find that all quality bins these days have superb transmission, so I don't consider the differences at all important even though, technically, they exist.

But then Dennis sez:
Transmission makes a big difference
Click to expand...

My question is - and maybe Bill will come back to answer it - where does all the light go that isn't transmitted? No doubt some of it is reflected back out the front, but not all.
If some of the lost light leads to a contrast loss on top of a transmission loss, then you're getting to the point where it begins to matter.
 
WJC said:
It is amazing and frustrating to me how people want to blame everything related to binocular observing ON THE INSTRUMENT, with almost no regard for the different physiology between observers, where a HUGE part of the differences would come into play. It seems that some people think because THEY don't understand it, it doesn't exist.

"Stacking BBs all night long ... daylight come an me wan go home." :cat:

The other Bill
Click to expand...
The other Bill. If I see a difference in the brightness between a high transmission binocular and a lower transmission binocular that are equal in other respects like exit pupil and coatings that rules out physiology doesn't it?
 
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wdc said:
Alexis sez:
I find that all quality bins these days have superb transmission, so I don't consider the differences at all important even though, technically, they exist.

But then Dennis sez:
Transmission makes a big difference


hmmmmm... real world experience vs. quoting transmission percentages on a forum? I wonder.
:)

-Bill
Click to expand...
"The last 6x30 I ordered (and returned) was from Maven. Why did I return it? One reason was that I tested it at dusk sitting in the house looking out at the yard, including the birdfeeder. As a companion to compare it with, I used the Leupod Yosemite 6x30. The Leupold was visibly brighter in low light compared to the Maven. My wife observed the same result. Maybe that is just Porro vs. roof optics, both with decent coatings, I don't know. The Maven was a sweet little ergo/mechanical package, but it wasn't necessarily better optically, and it was 5x the price."

Bill. Don't you think your observation would be an example of observable transmission differences possibly because of the differences between porro vs roof optics?
 
[email protected] said:
"The last 6x30 I ordered (and returned) was from Maven. Why did I return it? One reason was that I tested it at dusk sitting in the house looking out at the yard, including the birdfeeder. As a companion to compare it with, I used the Leupod Yosemite 6x30. The Leupold was visibly brighter in low light compared to the Maven. My wife observed the same result. Maybe that is just Porro vs. roof optics, both with decent coatings, I don't know. The Maven was a sweet little ergo/mechanical package, but it wasn't necessarily better optically, and it was 5x the price."

Bill. Don't you think your observation would be an example of observable transmission differences possibly because of the differences between porro vs roof optics?
Click to expand...

Thats what I was thinking. I can't prove it, but it did make me wonder.
 
fotbg said:
(a) will transmission be different for two given binoculars equally constructed the same, but with different magnifications and objective sizes?

(b) Will the transmission value be better on the binocular with larger exit pupil?
Click to expand...

answer to (a): No
answer to (b): No

-Omid
 
Light is absorbed into the glass or reflected, or transmitted.

I suppose strictly speaking absorbed light will lead to a slight heating of the glass.
Reflected light can be mitigated by good design, baffling etc.

Painting the inside matt black.
With professional lenses edge blackening is tuned to the actual glass material, which differs in different elements.

Exotic glasses need coating immediately they are made as they will immediately degrade.

However, with such simple things as binoculars, these problems are much less severe than a 30 element movie lens.

Old binoculars had poor transmissions, maybe 60%.
I have a Leitz 7x50 which gives a very good view despite no coatings.

Binoculars can have high transmission but have awful glare and flare.

Design is all important.

B.
 
[email protected] said:
The other Bill. If I see a difference in the brightness between a high transmission binocular and a lower transmission binocular that are equal in other respects like exit pupil and coatings that rules out physiology doesn't it?
Click to expand...

It does not because you are speaking of one person ... you. The main thing to remember is that—without all the comparisons—you are just trying to please yourself, which is good enough. Every time there's a shooting in my country—mass or otherwise—Socialists come out of the woodwork to blame guns. Why? because it's much easier to blame an inanimate object than the real cause. And because doing so might cause proponents to lose popularity at the ballot box. There is no law that says in order to be a voter, you have to have the capacity to think.That comment was not political. It was just a comment on common sense. :cat:

"Common sense is the least common of all the senses." — Mark Twain

Bill
 
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As with many things discussed on this forum - as they include consideration of both vision and perception (eye and brain) - what at first might seem to be both clear and simple is often not the case

And in relation to the particular topic there is also a fundamental distinction between:
- objectively measurable transmission by electronic equipment, and
- subjectively perceived brightness by a user

With transmission, we have the great body of work by Gijs van Ginkel to draw on at: https://www.houseofoutdoor.com/verre...n-vergelijken/
EDIT: the correct address is: https://www.houseofoutdoor.com/verrekijkers/verrekijkers-testen-en-vergelijken/ (thanks to cdmackay in post #21)

With perceived brightness - and especially the role of contrast - see the work of Tobias Mennle, starting with: http://www.greatestbinoculars.com/allpages/articles/itsthebaffling.html
(Tobias is a professional photographer, and many of the points that he makes will be familiar to those aware of considerations about photographic imaging)


Additionally as Bill Cook stresses in post #6, there are also substantial differences between individual observers
e.g. in threads about particular binoculars, see the sometimes heated disagreements about perceived image qualities including brightness and colour

In choosing a particular binocular, there’s always a mix of factors to be considered and unavoidable trade-offs to be made, including in relation to the image as perceived by the particular user
As always this stresses the obvious: where at all possible, try before you buy (or if buying on-line, make sure you can if needed return after trying)


John
 
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WJC said:
It does not because you are speaking of one person ... you.

Bill
Click to expand...

Bill

I see two aspects of your answer. The first speaks in favour of Dennis because his example seems to rule out his personal physiology. So I don't think he was wrong in this respect.

The second aspect, which is what I think you had in mind, is that his example doesn't rule out a different result from a different person whose physiology does have an impact on the result.

Love the quote from Mark Twain by the way.

Lee
 
The discussion about transmission and brightness returns regularly in this forum. Transmission is a given and measurable property of an optical system and it can be measured very accurately with the proper equipment.
Brightness on the other hand is a psychological property being the combination of the amount of light (transmission and exit pupil) and the color balance of the transmitted light.
Because of the confusion with regard to the discussion about it I have a couple of years ago made a literature study and I brought a lot of data together in a paper with the title "Color vision, brightness, resolution and contrast in binocular images "May 2013. It is published on the WEB-site of House of Outdoor.
Gijs van Ginkel
 
Gijs van Ginkel said:
Brightness on the other hand is a psychological property being the combination of the amount of light (transmission and exit pupil) and the color balance of the transmitted light.

Gijs van Ginkel
Click to expand...


Gijs

I am sure you meant to finish off the above sentence something like this:
.......the color balance of the transmitted light, and they way in which your eyes/brain system interpret these.

Lee
 
Troubador said:
Bill

I see two aspects of your answer. The first speaks in favour of Dennis because his example seems to rule out his personal physiology. So I don't think he was wrong in this respect.

The second aspect, which is what I think you had in mind, is that his example doesn't rule out a different result from a different person whose physiology does have an impact on the result.

Love the quote from Mark Twain by the way.

Lee
Click to expand...

Lee,

The first thing to be said about such discussions is that I really don’t give a rat’s butt; I just get involved because I know some others do.

The issue can be taken to whole new level by those NITNOIDY enough to do so. ONE observer will not have the same perception on different days and under different conditions. In fact, their perceptions could change more than once ON THE SAME DAY owing to alcohol, caffeine, drugs (prescription or illegal), fatigue, pain (especially headaches), tension, direct or ambient light, angle to—and intensity of—the source of that light, or even too much or too little water in the system.

When I was young and stupid enough to conduct—drum roll, please—TESTS, I found that on SOME days, with my first binocular of the day (I used the same binocular for ALL the tests) I could collimate without a collimator to 10-15 minutes. On other days, the best I could do was a degree to a degree and a half.

And those nitnoidy enough to worry about (aboot for our Canadian friends) that need to understand that a binocular made at 9:00 a.m. on Monday may not perform the same as the SAME PRODUCT produced on Tuesday at 2:30 p.m.. But as Aristotle so forcefully said ...

“WHO BLOODY CARES?!”

The attached graphic is from Dick Suiter’s book on star testing astronomical telescopes. You may take SPIDER OBSTRUCTION, SECONDARY OBSTRUCTION, and TUBE CURRENTS out of the equation but still see there is enough to worry about for all those who are prone to do so.

In professional optical system design, such things MAY matter. In discussions of consumer binoculars ... they don’t. They do provided observers with an endless amount of non-essential things to talk about, and talk about, and talk about. :cat:

Lee: on Twain,

“Writing is easy. All you have to do is cross out all the wrong words.” — Mark Twain

Cheers,

Bill
 

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Transmission and brightness are technically different things. Different people see things differently. The same person can see things differently at different times. This is why, when doing practical reviews (rather than quantative instrument measurements) of binoculars, the best reviews are comparative. This is why it is useful to read multiple reviews by the same author to get a sense of his/her preferences and sensitivities. Of course, individual units can also vary, so the strongest claims report attributes observed when examining multiple units of the same model.

In another current thread in BirdForum, I commented on the brightness of the Nikon 78ED Fieldscope versus the 82ED. My comments are based on side-by-side comparison of those two scopes and are written by someone who is sensitive to many aspects of the differing personalities of binocular models but who doesn't see much practical difference for birding between excellent quality scopes.

--AP
 
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