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Old August 19th, 2011, 12:09 PM   #1
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Shooting in a lab with inactinic (yellow) light

Anyone have any suggestions on how to correctly white-balance for yellow inactinic light (photo-sensitive safelight). Would just using a white card for calibration work or is it more complicated.
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Old August 19th, 2011, 12:54 PM   #2
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Re: Shooting in a lab with inactinic (yellow) light

Andrew,

If this is a typical photo lab safelight, there will be absolutely no blue in the light. Some safelights are red, some are amber. This is so the light will not fog the light-sensitive materials like enlarging paper or some types of film. Those materials are sensitive to blue, and some also to green and yellow-green. With this limited-color light source, there's no way to get normal-looking color in your video.

Those safelights are usually pretty dim, so you would want to have the white balance adjusted in a way that would not decrease the camera sensitivity the the safelight color. I'd suggest manually setting the balance to daylight, since that would tell the camera that there's more blue light than red and yellow, so the camera would favor the red end of the spectrum. That way you would get the best exposure for reds and yellows. Since there are no blues in a safelight, a decrease in the camera's blue sensitivity won't matter.

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Old August 19th, 2011, 02:40 PM   #3
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Re: Shooting in a lab with inactinic (yellow) light

From experience I shoot in 3200K preset.
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Old August 21st, 2011, 12:21 AM   #4
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Re: Shooting in a lab with inactinic (yellow) light

If the other colours are not there, they are not there. My personal preference would be to leave best be if the audience knows it is a photo lab.

Alternatively, I might try a TrueCut Ir filter as with lens iris wide-open you might be getting some infra-red as well from the lights.

If the colour is sickening to look at, in post I might try desaturating to almost black and white and then adding a bit of blue hue and maybe a bit of green hue.

Last edited by Bob Hart; August 21st, 2011 at 12:21 AM. Reason: error
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Old August 21st, 2011, 10:18 AM   #5
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Re: Shooting in a lab with inactinic (yellow) light

Quote:
Originally Posted by Andrew McWeeny View Post
Anyone have any suggestions on how to correctly white-balance for yellow inactinic light (photo-sensitive safelight). Would just using a white card for calibration work or is it more complicated.
White balance is the balance between red and blue light. In the case of a darkroom safelight, there's very little red and zero blue. None. So the concept of white balance is moot. Can't be done.

What you can do is set your camera's white balance to tungsten more or less and let it go at that. Darkrooms aren't supposed to look "normal" and what you'll capture will reflect just that, which is perhaps a good thing.
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