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Old October 7th, 2011, 11:49 AM   #1
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About gels

I just bought a 160 LED on-camera light that came with three gels, one white, one orange and one light magenta. In what situations would I use the orange and the magenta? Would there be any difference between them and just using the white one all the time and do custom white balance?
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Old October 7th, 2011, 12:35 PM   #2
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Re: About gels

Sebastian,

Your light probably has a daylight color balance. The orange filter would change the color balance to tungsten, useful if you're also using some tungsten lights in the scene.

As for the light magenta filter ... most fluorescent lights, and apparently some LED lights, produce a slightly greenish cast. Not a really strong cast, but enough that it can be objectionable in some circumstances. It's not really a color temperature problem, so doing a white balance wouldn't get rid of it. Magenta is the complement of green, so a light magenta filter can remove the green cast.

And the "white" filter would be a diffusion filter, to make the light seem less harsh.

Ken
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Old October 7th, 2011, 12:57 PM   #3
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Re: About gels

Thanks for your reply. So the orange gel, I would need to use it indoors with all tungsten lights? How would that be different from leaving the white gel on and doing a custom white balance?
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Old October 7th, 2011, 04:10 PM   #4
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Re: About gels

The goal is to get all the lights the same color. If you white balance for lights of mixed colors, you would get an average balance, but it could look kind of weird, with one side of the subject looking a little warm, while the other side looked a little cool. Granted, sometimes you have to settle for that, but it's good to avoid the miss-match when possible.

I'm reminded of the analogy of the man who is standing with one foot in a bucket of ice water, while the other foot is in a bucket of boiling water. On average, he should be quite comfortable. ;-)

Ken
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Old October 9th, 2011, 04:51 PM   #5
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Re: About gels

I shot a wedding last night and I tried using the yellow gels, but the truth is even with the other lights being very warm, this yellow gel cast an awful yellowish tint on people's faces that I fond awful. Taking off the gel or using the white one gave me a much more natural color.
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Old October 9th, 2011, 05:22 PM   #6
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Re: About gels

Remember you have different intensities such as 1/4 1/2 etc.

CTO converts Daylight balanced 5600k or 5500k to 3200k and even a full CTO about 2 stops or 1 stop cant remeber whereas CTB looses about 2-3 stops.

All the best
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Old October 18th, 2011, 06:18 AM   #7
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Re: About gels

hi sebastian,

"colour temperature blue" converts tungsten light to match daylight

full ctb .......converts 3200k to 5700k
3/4 ctb.......converts 3200k to 5000k
1/2 ctb ......converts 3200k to 4300k
1/4 ctb.......converts 3200k to 3600k

"colour temperature orange" converts daylight to match tungsten

full cto......converts daylight to 3200k
1/2 cto......converts daylight to 3800k
1/4 cto......converts daylight to 4600k

the magenta filters are minus green and come in full, 1/2, 1/4, 1/8.
(colour temps based on lee filters)
the white filter is probably a diffuser

depending on the native balance of your led you use the filters to match the dominant
light source for the scene
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Old October 18th, 2011, 06:57 AM   #8
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Re: About gels

@Sebastian
Yellow? Why did you use yellow?

When matching a dayllight LED to indoor tungsten lighting, you should use the orange gel that came with the light. "CTO" means Color Temperature Orange. As pointed out, these are specific shades of orange that balance color temperature.

It sounds like you used auto white balance? If so, that can throw things off as the AWB can choose the wrong color for white to balance to. When you blast out an area with a light, AWB may choose a good setting when you point your camera at the mainly lit area, but the areas not lit by the light will be off. Also, as you change camera angles away from directly at the lit area, the camera's AWB will change and try to average the temperature ... so mostly nothing is great looking ... maybe everything is off.

So if you are using indoor lighting, set your white balance for indoor. If you use outdoor lighting ... better yet, use a custom WB on location. Some cameras let you setup several custom WB settings.

When dealing with mixed color temperatures, use a white card to set a custom white balance. You put the card in the actual lighting, point the camera at it, and set the WB which tells the camera "THAT'S WHITE, deal with it."

If you want to step up to some of these advanced shooting topics, you'll benefit looking around for a tutorial on color temperature and lighting. The book "Lighting for Digital Video" by John Jackman is an easy read with good illustrations. There are others I'm sure.
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