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#1 Robert Glenn

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Posted 02 November 2005 - 10:17 PM

I was watching this movie ( http://www.imdb.com/title/tt0118548/ ) today at work, and I noticed that the fluorescent lights for the police office scenes were white, but the windows (presumably where sunlight was coming in) were all purple! I'm thinking that the cinematographer put an FL filter on, but I was expecting him to shoot with an FL-B and use tungsten, but with the purple haze, I guess he used an FL-D? I Would like to know if anybody would know which setup would cause this.. Also... how can the purple haze be avoided for this type of setup?
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#2 David Mullen ASC

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Posted 02 November 2005 - 10:53 PM

Correction filters on the camera can't correct mismatches between lights -- they can only correct the overall image one direction or the other. So if the lights have green in them and the windows don't, then a camera filter isn't really going to fix that -- your choices are to either filter the camera or correct the image in post to remove the green tint to the lights, causing the non-green lights in the frame to go magenta, or to leave the green lights green so that the non-green lights don't go pink.

The real solution would be to either gel the green lights to be less green (add magenta, i.e. Minus-Green gel), or use less green flos to begin with, or add green gel (i.e. Plus-Green gel) to the windows to give them an equal amount of green -- THEN you could filter the camera or correct it in post to remove the green.

FLB versus FLD just assumes that the flos are Cool Whites (blue-green), which are aprrox. 4800K (daylight is 5500K). FLB has an orange component added to the magenta to correct some of the blueness of the Cool Whites for 3200K tungsten-balanced film stock.
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#3 Robert Glenn

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Posted 04 November 2005 - 09:02 AM

Correction filters on the camera can't correct mismatches between lights -- they can only correct the overall image one direction or the other. So if the lights have green in them and the windows don't, then a camera filter isn't really going to fix that -- your choices are to either filter the camera or correct the image in post to remove the green tint to the lights, causing the non-green lights in the frame to go magenta, or to leave the green lights green so that the non-green lights don't go pink.

The real solution would be to either gel the green lights to be less green (add magenta, i.e. Minus-Green gel), or use less green flos to begin with, or add green gel (i.e. Plus-Green gel) to the windows to give them an equal amount of green -- THEN you could filter the camera or correct it in post to remove the green.

FLB versus FLD just assumes that the flos are Cool Whites (blue-green), which are aprrox. 4800K (daylight is 5500K). FLB has an orange component added to the magenta to correct some of the blueness of the Cool Whites for 3200K tungsten-balanced film stock.

David thanks for the explanation. The police office was quite large so replacing the lamps with kinos was probably over budget. Was strange that the windows weren't gelled though if that's all that was required. Is it hard to gel windows from the inside? Is there some type of adhesive gel that can be used?
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#4 David Mullen ASC

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Posted 04 November 2005 - 12:51 PM

David thanks for the explanation. The police office was quite large so replacing the lamps with kinos was probably over budget. Was strange that the windows weren't gelled though if that's all that was required. Is it hard to gel windows from the inside? Is there some type of adhesive gel that can be used?


Sure you can gel windows from the inside, but it has to be cut and taped incredibly well, which is time-consuming. There are hard acrylic sheets that can be cut and fitted to the window frame and there are gels with a sticky side to them, etc. All costs time and money.

It may be something as simple as making an artistic decision on the set to let the flos look a little green, and then in post changing your mind and trying to time the green out.
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