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#1 Natalie Saito

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Posted 07 May 2007 - 03:05 PM

when shooting with mixed sources, daylight and tungsten light:

is it better that the lights be color-corrected to match the film? (daylight balanced or tungsten balanced film) or does it not matter?

how much do daylight bulbs usually cost and can they be placed onto any type or brand of tungsten light? thanks.

Edited by NSaito, 07 May 2007 - 03:06 PM.

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#2 Natalie Saito

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Posted 07 May 2007 - 03:45 PM

i'm confused about plus/minus green gels. minus-green is supposed to remove greenish tint from fluorescent light. does plus-green increase color temp (to match daylight) and minus-green decrease it (to match tungsten)? thanks again!

Edited by NSaito, 07 May 2007 - 03:46 PM.

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#3 Michael Nash

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Posted 07 May 2007 - 04:35 PM

Typically you choose the film stock to match the predominant light source you'll be using, and gel or correct any other light sources that don't match in color temperature (assuming you want them to match and not appear a different color on your film). But sometimes you have to choose which film will have the speed, grain, and color rendition you want and strive to make you light sources match that.

Tungsten movie lights rarely have a "daylight balanced" bulb, although there are some dichroic-coated bulbs like PAR 64's. There are daylight balanced bulbs for practical like this: http://www.replaceme...om/lampbca.html

Otherwise you need to use full CTB gel on tungsten lights to balance them for daylight, which soaks up about 2 stops of output. HMI's are daylight balanced, and there are daylight balanced tubes available for Kinoflos and similar fluorescent units (including typical 48" T-12's found in commercial buildings).

Plus-green and minus-green gels don't change the color temperature of the light, they control the "green spike," or excess of green frequency, in the spectrum of fluorescent lights. Putting minus-green gel on a fluorescent fixture "neutralizes" the green spike, leaving the color temperature untouched (in theory). Cheapo Cool-White fluorescent tubes are usually about 4300 degrees kelvin, pretty much exactly half-way between daylight and tungsten. There are other "flavors" of fluoroescent tubes with different color tempertaures, and different intensity of green.

Adding plus-green gel to tungsten or HMI lights theoretically adds the green spike into the spectrum, so that those lights can be mixed with fluorescent lighting. You then match your color temperature up or down with CTB or CTO, depending on the lights you're using.

In reality you always have to test different densities of gels to get an exact match between different light sources. You can use the numbers as a starting reference, but you usually end up adjusting the densities a little, this-way-and-that.

http://digitalconten...g_green_plague/
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