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Light temperature for B/W


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#1 Albert Smith

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Posted 05 April 2007 - 06:20 PM

I am DOPing a short on 16mm b/w (first work lighting for film rather then video) and I was wondering if it really mattered to gel lights, the obvious answer seems to be no but for some reason that seems wrong to me, so does it matter? itd be nice to not have to gel down lights as I think there well be some interior day stuff that I will want to get all the power I can get out of our 2ks.

thanks alot for any information on this.
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#2 Nick Mulder

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Posted 05 April 2007 - 06:45 PM

Depends on the stock - but yes there are significant enough effects on EI with many stocks under tungsten and daylight conditions ...

eg. Plus-X Daylight 50/18 - Tungsten (3200 K) 40/17 - indicating it is more sensitive to the shorter wavelengths ...

I think thats pretty indicative of most other B+W types also
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#3 David Mullen ASC

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Posted 05 April 2007 - 07:07 PM

Generally, no, don't bother gelling the lights. Just realize that the b&w stocks are slightly less sensitive to tungsten lights than daylight lights (but it's not a big difference.)
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#4 Jonathan Bowerbank

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Posted 05 April 2007 - 07:28 PM

Just curious if anybody's ever gelled their lights red to hide blemishes when shooting b&w. I know a red filter is used often for this, but I've never heard of people gelling the lights for it. Or possibly green to enhance blemishes? ha ha
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#5 David Mullen ASC

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Posted 05 April 2007 - 08:00 PM

Sounds like an interesting idea.

One of the b&w versions of "Dr. Jeckel and Mr. Hyde" used a trick where the Mr. Hyde make-up was in one color and the Dr. Jeckel make-up in the opposite, so when they faded from green to red lighting, I believe, on panchromatic stock, the make-up effect faded in or out to create the transition in-camera.
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#6 K Borowski

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Posted 06 April 2007 - 12:05 PM

Generally, B&W movie stock needs more exposure when printed to film or transfered to video than it would were it to be printed to photographic paper as it is in still photography. For that reason (this is also why cine lenses bother with the hastle of calibrating in T-stops), you may want to consider that film is 1/3 of a stop less sensitive under tungsten light than under 5000K daylight. That means your 200 speed daylight negative film should be exposed at 160, or even 125 with it rated at 160 normally when exposed under tungsten lamps. Just remember that if there's doubt, you want to overexpose rather than underexpose.

This may seem like a small amount, but there is a definite loss of speed under tungsten. I shot some B&W stills back in the day, before I knew the 1/3 stop sensitivity loss, and I lost shadow details because I didn't account of the color temperature.

Basically, this is because, while panchromatic film is sensitive to almost all of the colors of the visible spectrum that the human eye is, it is natively sensitive to blue/ultraviolet wavelengths that predominate daylight but are lacking for tungsten bulbs.

I have no clue on fluorescents. THey're so ugly, and flicker so much I'd honestly just avoid them.

You can still get 3400K movie bulbs (I think 250) that will fit in wall sockets at Photographic Suppliers. I'd recommend them as they work great in a crunch for supplemental or background lighting.

~Karl B

Oh, one more thing lest I forget. Do NOT filter B&W for color temperature unless you want to adjust the TONALITY of a specific color as it relates to the greys of the other colors as they show up on the negative. In other words, if you want reds to pop out on a rose you're shooting with B&W, you can use either a red or a green filter to heighten the contrast between the two colors. Red'd be best here as it would darken the green (on the print, it'd physically block out green light on the negative), and lighten the red.

Edited by Karl Borowski, 06 April 2007 - 12:08 PM.

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