Black and white lighting possible?

[jtr1962]

I was just wondering if it is possible (with LEDs or otherwise) to light objects such that they just appear in shades of gray (i.e. zero color rendering). No particular reason for doing so but just curious if it was theoretically possible.

P.S. Don't mention low-pressure sodium lamps since those may give zero color rendering but also a yellow overtone. I'm interested in zero color rendering with a neutral (i.e. grey) overtone similar to the old black and white movies.

[sniper]

I personally don't know of any light that produces such a narrow spectrum of emissions, but there well may be.

The "standard" for photography lights is: Daylight film: Clear, open sky, ~ 5600-6100 degrees Kelvin. (Lots of blue) Tungsten photo lighting: 3400 degrees Kelvin, (Yellowish cast on daylight film) and household tungsten incan lamps, 3200 deg. K. (more yellowish, tending to red, like incans on low batteries.) Tungsten balanced film is available, but expensive.

The old movies' effects were produced by a combination of othochromatic film (no red sensitivity) and well-controlled lighting, (That's why leading ladies' lipstick looks black or dark grey in the old flicks.) until panchromatic film became available. Then they used filters. "Night" scenes were done in broad daylight, by placing a red filter over the lenses, and underexposing. Same thing with color film nowadays, but a neutral density filter is used, when it is not actually night.

If you wish black and white effects from normal, everyday scenes, invest in some black and white film, and have at it. Some companies, like Kodak and Ilford make black and white film that can be processed in color chemistry, but you may have trouble convincing some 17 1/2 year old processing person that it won't pollute the machine chemistry.

Of course, digital has got it whipped with auto or custom white balance features, and photoshop, which can make beautiful black and whites from your color images. Shoot it in color for better detail, then convert to B&W.

[Wim Hertog]

Originally Posted by jtr1962

I was just wondering if it is possible (with LEDs or otherwise) to light objects such that they just appear in shades of gray (i.e. zero color rendering). No particular reason for doing so but just curious if it was theoretically possible.

P.S. Don't mention low-pressure sodium lamps since those may give zero color rendering but also a yellow overtone. I'm interested in zero color rendering with a neutral (i.e. grey) overtone similar to the old black and white movies.

I don't think thats possible. To create white light, you need at least 2 colors (for example blue and yellow). You'll see yellow objects as yellow and blue ones as blue...

[jtr1962]

Originally Posted by sniper

Of course, digital has got it whipped with auto or custom white balance features, and photoshop, which can make beautiful black and whites from your color images. Shoot it in color for better detail, then convert to B&W.

I'm aware that it's quite easy to convert color to B&W digitally, or to shoot scenes with B&W film. I was really interested in whether it was possible to light a scene so it looks B&W seeing it with my own eyes, without any special glasses, either. Still, really interesting info you posted, so thanks! Iwasn't aware that they used to shoot nighttime scenes during the day when they used B&W film.

[jtr1962]

Originally Posted by Wim Hertog

I don't think thats possible. To create white light, you need at least 2 colors (for example blue and yellow). You'll see yellow objects as yellow and blue ones as blue...

Hmm. I wonder if combining LPS with a single wavelength blue emitter of the appropriate frequency would do it? I did once try Tokyo blue and amber LEDs. They made a nice synthetic white with pretty poor color rendering, but since they were both narrow-band rather than monochromatic emitters you still saw some colors. Still, it was a pretty creepy effect-the colors were really distorted. I have to try one day using enough of these two colors to light a fairly large area and see what the result is.

[IsaacHayes]

Impossible, since the colors you see are a result of the color of the objects reflecting back the light they don't absorb. You'd have to have a totally monochromatic light (single color) or shine the light on objects that were B&W to begin with.

EDIT: you can do the poor color rendering stuff with 2 colors like a r/o luxeon and a cyan luxeon that is heavily towards blue (S1JC bin). You'll see white light mixed in the center, but color rederign will likely be odd.

[greg_in_canada]

The only way I can think of is to light it so dimly that your vision becomes monochrome (i.e. moonlight lighting levels).

Greg

[bfg9000]

I saw a science museum exhibit years ago, where the guests walked under colored spotlights and everything underneath turned black and white to the eye. It was very unusual to see people inches away drained of color like an old movie! You could look around the room or up at the filters and see color, but everything under the hot lights was in black and white. I recall it wasn't perfect because eg some especially bright greens still had tinges of color, but the blues and reds turned absolutely to shades of gray.

So it is possible to fool the eye, but I have no clue how they did it. I did take a color photograph, but the film was not as fooled.

[jtr1962]

Originally Posted by bfg9000

I saw a science museum exhibit years ago, where the guests walked under colored spotlights and everything underneath turned black and white to the eye. It was very unusual to see people inches away drained of color like an old movie! You could look around the room or up at the filters and see color, but everything under the hot lights was in black and white. I recall it wasn't perfect because eg some especially bright greens still had tinges of color, but the blues and reds turned absolutely to shades of gray.

So it is possible to fool the eye, but I have no clue how they did it. I did take a color photograph, but the film was not as fooled.

I'd guess that they probably used a narrow band blue and yellow filters, and then mixed the blues and yellows in proper proportion to get a neutral tint. The fact that you could still see some green is what leads me to believe they did it this way. A object can appear green either by reflecting back green light, or by reflecting back blue and yellow.

It's good to know I'm not the first one who wanted to do this. I think it would be a cool effect where you have a room mainly lit with narrow-band blue and yellow so as to give a monochromatic effect, but had white light focused on a few colorful objects.

[evanlocc]

There was once in my mind that use color paper as a filter in front of a flashlight and give the same color right.

But how about a black color paper filter...

[dcarch8]

In the world of anti-matter, where a parallel world exists but runs in the opposite direction, a flashlight, when you turn it on, will "shine" a beam of black where ever you are aiming it.


dcarch8

[FirstDsent]

Interesting,

I wonder if there's a bizarro CPF website there where people post threads about darkness and shadows: "Bizarro Lumileds just revealed the darkest LED ever!". Or: "I just got my new bizarro SureFire 10X. I went out yesterday at noon and I couldn't see a thing -awsome!"

Bernie