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Lens tint color matter?

Printed From: OpticsTalk by SWFA, Inc.
Category: Other Optics
Forum Name: Binoculars
Forum Description: Anything that requires two eyes to look through it
URL: http://www.opticstalk.com/forum_posts.asp?TID=43482
Printed Date: October/23/2017 at 03:04


Topic: Lens tint color matter?
Posted By: Brocksw
Subject: Lens tint color matter?
Date Posted: October/20/2016 at 20:28
I've noticed Zeiss, Leica, Swaro all have a somewhat different color tint to their glass... Does this serve a purpose or aid in any performance measured areas or is it just cosmetic thing? I'm sure someone could respond about colors in the electromagnetic spectrum or certain colors reflecting more light than others...but how much of it true?



Replies:
Posted By: anweis
Date Posted: October/20/2016 at 20:54
The different colors do not matter to the end user. They are different because of different materials, methods, minerals, and chemicals used to coat the glass to allow more light to pass through and less light to be reflected. The coatings are called "anti-reflective coatings". 


Posted By: Brocksw
Date Posted: October/20/2016 at 21:12
So I was aware of lens coatings and their significance, but if I'm understanding you correctly the color tint is just the unique result of each companies proprietary lens coatings materials?


Posted By: supertool73
Date Posted: October/20/2016 at 21:51
Exactly

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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: WJC
Date Posted: October/21/2016 at 00:14
What is seen as a "color" isn't. It represents the wavelength being reflected. Thus, there isn't really a "tint."


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"However elegant the strategy, you should occasionally look at the results.—Winston Churchill


Posted By: supertool73
Date Posted: October/21/2016 at 10:10
Originally posted by WJC WJC wrote:

What is see as a "color" isn't. It represents the wavelength being reflected. Thus, there isn't really a "tint."


Bill, would you expound on this more.  Why do they focus on different wavelengths etc, and how that affects the image at our eyes?

Thank you sir.


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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: Klamath
Date Posted: October/21/2016 at 10:48
The way I look at this issue is that the color tint we see (due to the wavelength being reflected as Bill states) is a way for each high end maker to put a signature on the view of their binocular.  Leica and Nikon favor a warm color bias (tint), Swarovski a neutral one, and Zeiss typically uses a cooler color tone.  Look at it like what flavor of sunglass lens do you like, that sort of analogy.  That tint is the result of deliberate design parameters.

As a slightly different example, why do our eyes survive a top end glass transmitting 90%+ of light at 10x...because coatings filter out damaging UV ray wavelengths.  Different coating regimes can feature different wave length transmission and effect the overall light transmission curve, and thus the color tint/bias..




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Steve
"Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted". William Bruce Cameron



Posted By: WJC
Date Posted: October/21/2016 at 11:02
They give the warm, cool, or natural hues the consumers desire. The manufacturer really doesn't care. He just wants to push boxes out of the plant. Surveys show, however, what they target audience likes best.

In the late 50s and early 60s some binos had beautiful blue "tinted" lenses and people thought they were seeing better. In conversation with Humphrey Swift, I learned that beautiful coating was a byproduct of magnesium fluoride being deposited at too low a temperature.

Finally, take those silly "Ruby" coatings. They will, in fact, bring out a BROWN dear against a GREEN foliage background (target audience: hunters). But, only at the expense of slightly reducing the instrument's "effective aperture."

It wouldn't make a hill of beans to me. But, for some people, it is supremely important. "Sensory threshold" is a topic more people should look into.

 


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"However elegant the strategy, you should occasionally look at the results.—Winston Churchill


Posted By: WJC
Date Posted: October/21/2016 at 14:57
Hi Steve:

Whether the lenses were coated with the finest AR coatings or a thin layer of dog poop, it doesn't matter.
UNCOATED GLASS will stop UV at about 90% per millimeter!




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"However elegant the strategy, you should occasionally look at the results.—Winston Churchill


Posted By: Klamath
Date Posted: October/21/2016 at 15:02
Thanks Bill'

I had it in my feeble mind that there were UV coating involved...guess not...


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Steve
"Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted". William Bruce Cameron



Posted By: WJC
Date Posted: October/21/2016 at 15:07
No, No my friend:

I wasn't even speaking to that part at all; to me it is irrelevant:
13
“JUST HOW BAD IS ULTRAVIOLET?”

One of the biggest talking points among today’s binocular enthusiasts concerns the deleterious effects of exposure to ultraviolet light rays. There’s no doubt ultraviolet light is damaging to the eyes and other living tissue, and speculation on how much can liven up Internet forums for days or weeks, only to be recycled two or three more times before the year is out. Still, these speculations provide much more mileage to those who thrive on finding complex solutions to non-existent problems than furthering the science. Let’s look at the two primary reasons.

First, considering the structure of noses, brows, and cheekbones, the eyes of the average person walking down the street will be exposed to ultraviolet light from about 90 degrees in the vertical plane and 130 degrees in the horizontal. By simply putting a 7x50 binocular—the most prominent size for many applications and homes—to one’s eyes, that UV intake will be reduced to around 7 degrees in the vertical field and 7 degrees in the horizontal. It would seem then that nature is subjecting you to over 200 times more UV than you would be exposed to by using the binocular. These figures don’t address the measurement of light subtended on the retina. Still, it should be obvious that just placing the instrument in front of your eyes dramatically reduce the eyes’ intake of ultraviolet.

Secondly, ultraviolet rays are absorbed by glass alone—regardless of the coatings—by about 90% per millimeter, and the average thickness of an objective lens for a moderate size binocular is about 15- to 25mm. Hence, how much ultraviolet would be getting through such a system, even if we ignored the first consideration above or subsequent glass elements in the instrument?

Finally, I would like to offer a comment by Ed Huff, a binocular buff and former senior scientist with NASA:

“According to the attached chart, UVA, UVB, and UVC are virtually extinguished by the binoculars.”

 

 

 

 


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"However elegant the strategy, you should occasionally look at the results.—Winston Churchill


Posted By: Brocksw
Date Posted: December/29/2016 at 14:24
https://www.americanrifleman.org/articles/2011/4/8/optical-coatings/

I found this article in American Rifleman that spoke on this subject briefly...I was hoping someone could speak to the validity of what they discus...


Posted By: Bird Watcher
Date Posted: December/29/2016 at 18:49
Here's some additional information:

http://www.cloudynights.com/topic/3770-best-of-the-binocular-forum-start-here/#entry42018 - http://www.cloudynights.com/topic/3770-best-of-the-binocular-forum-start-here/#entry42018


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I prefer Porro prism binoculars especially those made in Japan. (i.e. Minox BD 10x44 BP) 8>)


Posted By: WJC
Date Posted: December/29/2016 at 22:05
Brocksw:

I scanned the piece in what little time I had available (it’s Christmas, and I have a granddaughter who can be 5 places at once), and found it to be quite informative. Like a brother from another mother, he points out that so many bugbears of the amateur observer are really inconsequential, as they are below the observer’s threshold of recognition. Amen to that.

There were a couple of points that could stand to be addressed. I would hurry on to say that, considering his audience, his approach was probably just fine.

First, he speaks of “light” as if one size fits all. The visible spectrum runs from ~.4 µ to ~.7 µ, with the center of human visual acuity being ~.580 µ.

This may explain why he puts the thickness of AR coatings at .000006-inch. I am certainly no math wizard—I’m not even adequate. However, I think the thickness—as if it amounts to a hill of beans to the end user—should be recognized as ¼ Lambda of the wavelength central to the design. Ilya: help me out here.

Also, for Steve:

Although I got the UV figures for my post of October 21 from a professor at the College of Optical Sciences at UA, I apparently didn’t investigate it thoroughly enough or note that he was speaking in generalities. Thus, I am offering a revised vignette on UV as follows:

14 “JUST HOW BAD IS ULTRAVIOLET?”

One of the more prominent talking points among enthusiasts concerns the deleterious effects of exposure to ultraviolet rays.

There’s no doubt ultraviolet radiation is damaging to the eyes and other living tissue, and speculation on how much can liven up Internet forums for days or weeks, only to be recycled two or three more times before the year is out. Still, these speculations provide much more mileage to those who thrive on finding complex solutions to non-existent problems than furthering the truth.

The Light

Considering the structure of noses, brows, and cheekbones, the eyes of a person walking down the street will be exposed to light from about 130 degrees in the vertical plane and 150 in the horizontal. By simply putting a 7x50 binocular—the most prominent size for many applications and homes—to one’s eyes, intake of light will be reduced to around 7 degrees in the vertical plane and 7 degrees in the horizontal. It would seem then that nature is subjecting that person’s eyes to many times more light than they would be exposed to by using the binocular, including seepage around, and reflections from, the rear eyelens.

Ultraviolet Radiation

We aren’t addressing light here, however, but ultraviolet radiation. So, exactly what frequencies of ultraviolet are we speaking of? UV-A extends from 315-400 nanometers. These are also the rays responsible for tanning, and short-term exposure doesn’t constitute and serious threat. UV-B rays are more dangerous and extend from 280-315 nm. However, in this region, transmission through even uncoated glass takes a nosedive, and along with the more harmful UV-C rays, extending from 100 to 280 nm, harmful effects are almost completely alleviated by the glass.  

One knowledgeable estimate places attenuation by glass—regardless of coatings—at about 50% per a 5-millimeter thickness. Based on this, Ed Huff, a binocular buff and former NASA senior scientist commented:

“If the full glass thickness through the binoculars were approximated as 20mm for objective, 60mm for prisms, and 20mm for the eyepiece, that would total 100 mm, or 20 5mm slices. The UV transmittance through the binoculars, therefore, would be .5^20 = .000095% —which qualifies as virtually extinguished.”



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"However elegant the strategy, you should occasionally look at the results.—Winston Churchill



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