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Lighting temperature Question for a green screen trial

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nelsonmay10
Lighting temperature Question for a green screen trial
on Feb 12, 2007 at 4:31:04 am

I am starting to do some chroma key work with a muslin green screen. I was given advice to use cool white flourecent bulbs on the screen to "pop" the green. It does do a good job. I am lighting my subject (me) with tungsten. My subject distance off the screen is about 10 feet and I am not detecting any spill. When I capture my footage, my skin has a very orange tone to it. Is that a mix of the lights (tungsten and cool white), or are my tungsten lights too close or too hot. I can do a min of 250 per soft box. If I can't do much with the lighting I have, can I add gels to change the color temp a bit on my softboxes or should I just add color correction in the post after I key?

thanks in advance



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todd mcmullen
Re: Lighting temperature Question for a green screen trial
on Feb 13, 2007 at 3:08:39 pm

sounds like you need to check the color temp of your camera. Use 3200 k and you shouldn't have "orange skin".

Todd McMullen
Flip Flop Films
Austin
Cinematography Forum Leader


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Tim Kolb
Re: Lighting temperature Question for a green screen trial
on Feb 19, 2007 at 2:46:48 pm

I like to light foreground subjects based on what they are being keyed over...I usually light for keying over exterior scenes with 5600K.

For most keying systems, the idea is to make the background as distinct as possible from the foreground...and as saturated as possible. Whatever does this and keeps the foreground manageable (you don't want to start color correcting yourself from purple or anything) should work, even if the background isn't a faithful reproduction of the green color.




TimK,
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Jon Elsdon
Re: Lighting temperature Question for a green screen trial
on Feb 4, 2008 at 2:33:35 am

We often use Kino flo florescent lights for green screen projects. They work well and you can buy bulbs specially designed for chroma key work. You should be able to get away with using those two different light types, but it isn't the most ideal situation. I wouldn't recommend adding gels to the tungsten lights. This was a technique more commonly used back when 35mm film was the main recording method of choice and white balancing was not a "One-Click" feature like it is on most current digital cameras. It sounds like you are white balanced to the fluorescent light instead of tungsten. Use white balance to remove the orange skin tone. Place your grey/white card at the location where the subject is and white balance to that. If you can't manually set white balance on your camera, the default tungsten setting should work ok. Keep in mind, when you white balance for the subject you are inherently going to change the tone of the green screen slightly because of the two types of lights being used. As mentioned in an earlier post, lighting your subject is directly connected to the scene they are going to be comped inside. The green screen on the other hand should always be exposed consistently.

Jon Elsdon

VFX Supervisor

EEFX.COM - Chroma Key Green Screens & Supplies


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