should some binoculars have a slight green tint?

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jamesgrant

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So I bought the Plastimo waterproof, fogproof Nitrogen filled binos. Got a very good deal (less than half price).

Probably would buy different ones now that I am armed with all the knowledge imparted by forumites.

But, when looking through the binos, should the view have a slightly green tint to it?

Is that the Nitrogen, or the red lining on the glass?
 
It is not unusual for a binocular to have a tint. Some are absolutely neutral like Fujinons but the Russian bins for example have a green/blue tint; Pentax used to have a very cold blue tint and some with that bright red coating on the front lenses, had a red tint. Swift binos always used to give a warm tint. I know that is not a colour but the image looked warm especially compared with a cold looking Pentax image. I believe it is a function of the coatings and modern coatings are brilliant even on cheap models.
 
My bins seem to vary with the subject.
Big white gas guzzlers stay white or perhaps I see red
Whereas eyeing a gorgeous Spirit yacht I certainly get a green tinge.
 
As actionoptics says, the green, blue, red etc., tints are usually antireflective coatings to cut down the internal reflections between the front and rear of the lenses. They do make for a much clearer image.
 
It's possibly the lens coating, but neutral grey lenses also appear to have a green tint, as the human eye more readily picks up green light. Take a look at a pair of Ray-ban sunglasses and you'll see what I mean.
 
Ray-Bans are green (deliberately).

a: -10.0 to -11.5
b: +13.2 to +15.2
IVT 15.5% –19.5% 2mm path

(I used to make the glass /forums/images/graemlins/cool.gif)

It is very, very difficult to get a truly neutral grey.

I agree that the colour cast through the bins is probably just a subtle effect of the lens coating - if it looks red in reflection, it's because it is transmitting more of the greens / blues. The eye's sensitivity peaks around 589nm which is greenish, so the coating is probably optimised for low light use, rather than for colour accuracy.

Andy
 
You're right. I was just going from ancient memory of the card that came with my over 20 years old Aviators. Compared them to an ND lens filter and they are definitely greener. Found this website with a description of the G15 lens and it says the formulation transmits colours in the way that our eyes are sensitive to them, allowing more natural vision (natural not neutral). My mistake.
http://www.bardoptical.com/html/sunglasses.html
G-15 Lenses

Historical Perspective

In 1951, in response to a Navy Air Corps requirement, Bausch & Lomb began developing a truly neutral sunglass lens, called the N-15. This lens was reformulated slightly to make it more suitable for prescription use and renamed the G-15. The military services were so impressed that they wrote a complete set of specifications around the characteristics of the G-15 lenses.

How the Lens Works

Human eyes do not respond equally to all colors in the visual spectrum. The eyes are more sensitive to green and yellow wavelengths and are less sensitive to red and blue. Based on this knowledge, the G-15 lens was formulated to emphasize the colors that our eyes see most easily and de-emphasize less useful colors.

The G-15 lens absorbs 85% of visibile light, transmitting only 15%. The light transmission curve of the G-15 (showing the amount of light that is allowed to pass through the lens) is similar to the color sensitivity of the human eye. What this means is that the lens transmits colors in the same way tha tour eyes are sensitive to colors. This results in natural vision - true colors that are easy on the eye.

The G-15 lens is made of impact resistant optical quality glass. It provides 100% Ultraviolet (UV) protection, is naturally scratch resistant, and has outstanding stability with virtually no time-related fading or alteration of the tint.
 
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