BlueMorel Loc: Southwest Michigan

Here is a photo I took with my cellphone of twilight clouds over my barn. A barn light in the photo looks green, which I've run into before when I take night shots. Sodium arc lamp, BTW.
What causes this? Fixes?

(Download)

Longshadow Loc: Audubon, PA, United States

Auto white balance used?
Have you tried changing the white balance?

pquiggle Loc: Monterey Bay California

Sodium arc lamps are yellow and mercury vapor lamps are green. The cause is the way light is produced by the sodium and mercury atoms they contain. If it either of these there is little you can do about the color as the light they produce is nearly monochromatic. If it is an older fluorescent type bulb with lots of mercury in it then white balance could help but that would shift the colors in the areas of the scene not illuminated by the light. In this case it would shift the sky toward magenta.

BlueMorel Loc: Southwest Michigan

(Face red) Yup, that did the trick! I have a Samsung Galaxy 6, which has pro settings I rarely use, including WB. Time for me to treat its camera with the same respect as I give my DSLR!

Longshadow Loc: Audubon, PA, United States

Phone cameras are getting better.

BlueMorel Loc: Southwest Michigan

Thanks for the explanation! The bulb was new in 2010 after a hailstorm knocked the old one out. Pretty sure it's a sodium one.

I will have to wait for another night where there is actually a sunset to test out the various WB settings. Might be awhile since we seem to have a permacloud hanging overhead for the foreseeable future.

Longshadow Loc: Audubon, PA, United States

pquiggle is right on the colors emitted for the two lamp types.
Unless the camera color balance was set to something other than auto.
My kitchen fluorescent tubes in my old house showed up green with daylight film.

User ID

Looks green cuz it IS green. Appears to be
a high voltage metal vapor lamp. Different
metals produce their characteristic colors
when vaporized. Some lamps contain more
than one metal ... others just one.

Vaporized metal is a gas. Neon is a gas. So
you've asked the same question as, "Why
does neon light up red ?"

FWIW, xenon lights up bluish white, similar
to daylight. Xenon is the gas in flash tubes.

Here's a image lit by sodium vapor, xenon,
neon, argon, mercury, phosphor and maybe
some others, all together but coming from
different angles at different intensities:

(Download)

larryepage Loc: North Texas area

I remember making a visible light spectrometer in physics using a narrow slit and a diffraction grating (more efficient than a prism, making a brighter image).

"Old" low pressure sodium arc lamps have two very closely spaced yellow emission lines. Their light is monochromatic yellow...no other colors can be resolved under them. These lamps are very efficient, though, and produce a lot of light per watt of electricity. More recently (the last 30 years or so), high pressure sodium arc lamps have been available. We installed these in our manufacturing plant to make labels with color information more easily readable. They look subjectively pretty much like white incandescent light, but are still not really good for photography. Mercury vapor lamps produce six main spectral lines...two closely spaced ones in each in of the orange, green, and violet parts of the spectrum. The result is light that appears blue-green in color. It is vaguely similar in color makeup to the oldest fluorescent tubes, but not exactly the same. In a pinch, I have used fluorescent white balance to produce usable images under mercury vapor.

These lights appear to me to most likely be mercury vapor.

traderjohn Loc: New York City

Yes, they are. How many young people, young married families do you see schlepping around camera bags or even DSLR's?

JohnSwanda Loc: San Francisco

The problem with changing the WB to get rid of the green from the lamp is that it will throw off the WB for the rest of the photo. I would suggest using the clone tool in color only mode and clone the color of the roof which is not green onto the green portion.

Silverman Loc: Michigan

From my newbie understanding, check your White Balance setting. I have also read some suggestions concerning the use of a "Gray-Card", this may be a more accurate way of determining the proper "White Balance" in your image. Other more experienced UHH members will be helpful to you.

fetzler Loc: North West PA

There is noting wrong with a green light looking green.

jerryc41 Loc: Catskill Mts of NY

Yes, it's interesting how a camera can see things our eyes can't Depending on what is inside that light bulb, colors can look different in the camera. LEDs might look like they're blinking through a viewfinder. You should be able to process that light white.

JohnSwanda Loc: San Francisco

The WB is fine. The light really is green. Correcting to make the light neutral would throw off the WB for the rest of the photo.