Well, in all honesty, I think you’re not so wrong. It’s one thing for our visual system to adjust for a tint, but adjusting for a deep monochromatic cast might well be different. Only one way to find out… I’m going to try modding some welder’s goggles.
Say, how about projecting an image of the real world onto those light-darkening glasses, the ones that turn darker after exposure to light? The brightest spots in the image would make the glass locally darkest there. Then, simultaneously, you look through the glass at a different angle at a white screen in the background. You’d see a negative image, and it would be in various shades of black and gray and white. The negative image you see would include all the wavelengths that you illuminated your white screen with. It’d completely lose the color information of the real world.
As long as we are being fanciful, if you object that the image is now a negative, then we string two of these assemblies together in series.
>Enough water filters out all color, but that doesn’t seem to be practical.
This is true, in the sense that pure water has a blue tint. As you have more and more water in the way, what little you can still see is just blue. But it takes a long length of water, and in nature such long paths through water usually include enough particles that it gets hazy faster than it gets blue. I hear, though, that the ocean around Antarctica is known for being very transparent and very visibly blue.
From 1954 onward, the majority of American movies were made in color.
“True” greyscale photography is a relatively new invention (in the sense of recording brightness in a fairly wide band of visible spectrum). In the '50s particularly, panchromatic film was still relatively new, and television performers routinely used green makeup for black-and-white cameras. Even with pan film, a green filter is said to enhance skin tones. After color TV cameras came in, I believe it was common practice to use only the green channel for black and white displays. At least, I know analog RGB video used to provide a sync signal on the green channel so it could be fed directly to a composite B&W monitor.
True. At least, I understand deep sea creatures tend to be red because at those depths red might as well be black, and (I gather) actual black pigment would be a needless expenditure of protein.
Blue lenses would probably replicate this effect, but I think green would be nicer to skin tones.
Perhaps Salmo only watched TV. 
Now that would be something–glasses that make everything Technicolor!
Here is what I’m thinking:
You have a twisted nematic liquid crystaline film that is photosensitive. Suppose it has a functionality on it like retinal. When light of the right polarity hits it, it will change the shape of the molecule causing the liquid crystalline structure to become disrupted so that light no longer passes through it. This is similar to the way a liquid crystal display works except that it is responding to light rather than a voltage. This will create a negative image on the film that is black and white.
The reason the film neads to be liquid crystalline is that in order to create the black and white image you have be able to pass a white light source through it that won’t cause the film to go completely black. So the light entering the device goes through a parralel polarized lense, while the white light projector goes through a perpendicular polarized lense.
This will result in a negative b/w image, if you want a positive image you would have to run it through the same apparatus again.
Does it have lots of problems? Yes, lots. Are you going to be able to wear it on your head? Not likely, but the way things can be miniaturized these days who knows.
I just wanted to say that that was a very good question, and an amazing array of erudite answers. I love this place.
I don’t follow how that removes color from the light that it transmits, but never mind. It might be easier just to hook up one or two of these to one of these .
(In case of link rot, those links are to a micro B&W video camera and a page of various “head mounted displays.”)
I thought water looked blue in large bodies because smaller wavelengths are filtered out, not because it actually has a blue tint?
>because smaller wavelengths are filtered out, not because it actually has a blue tint
I think you mean, “because larger wavelengths are filtered out”, right?
Those two things are identical. Filtering out the redder wavelengths leaves the bluer ones. Having a tint means being at least somewhat selective in which wavelengths are filtered out.
Here you go: Matrix Goggles. Also see here.
ETA: I guess it’s not quite an answer to the OP, which asked about a type of glass or plastic (lens) that would do it, but if your goal is to see in black & white, these would allow you to achieve that.
Isn’t there a difference? I thought with water it was scattering vs transmission, as opposed to absorption vs transmission in something like a gel filter.
You’re conflating two different media: film and television.
Eastman Kodak introduced panchromatic film stock in 1922, and stopped manufacturing orthochromatic film in 1930.
The green-replaces-red makeup for television was used in the late thirties and early forties. It was no longer necessary after the introduction of the image orthicon tube in 1946.
Sorry, I’ve read some really old photography books, and sometimes it runs together. I may have associated ortho emulsion with nitrate stocks as “old standards.” I know Nitrate was in use in the '50s because I still have some of Dad’s nitrate negs from that time in the freezer. I’m also sure ortho was available a lot later than '30, but I guess if Kodak wasn’t producing it it couldn’t have been in common use.
Am I incorrect that you use the green channel to feed a B&W monitor from RGB? I thought that’s why they put sync on green. Certainly the easy way to get decent greyscale from an RGB image used to be delete the red and blue channels, although I realize that’s not ideal.
Anyway, if you’ve got computational resources, there’s no need to pick a filter color. Just use a black and white display.
>Isn’t there a difference? I thought with water it was scattering vs transmission, as opposed to absorption vs transmission in something like a gel filter.
I think there’s a difference between scattering and absorption, but I don’t think “tint” indicates which mechanism is operating. And I know that scattering is the mechanism for a large category of gel filters. If you look at one of those graphs showing the transmission curves for various Wratten filters, for example, you notice there are many curves that have high transmission for longer wavelengths and low transmission for shorter wavelength, so they’re all a stairstep shape, an S laid over flat, characterized by a cutoff wavelength. You can get these with roughly any cutoff wavelength you like. There are so many of these because they all work by scattering and it’s easy to manipulate the onset of the scattering. This is also a reason there are so many reddish and yellowish and brownish colors in nature. The Wratten and other popular lines of filters also include curves that are more complicated, or that try to stop long wavelengths and pass short ones (though you notice these S’s are not so neat), for other reasons, but that big population of longpass stairsteps represents scattering technology.
I have to admit uncertainty about where the scattered light is going. The sky scatters the bluer wavelengths, and you can look at the sky and see the blue. I don’t think you can do this in water and see the red. A more thorough treatment of index of refraction as a complex number, where the imaginary part represents absorption by the Beers - Lambert - Bouger (sp?) laws, and the real and imaginary parts are coupled by the Kramer - Koenig (sp?) relations, ought to clear it up. But I tried working on this a year or so ago and just got frustrated.