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Exact color temperature shifts.


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#1 Zachariah C. Bensel

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Posted 11 July 2018 - 09:20 PM

Hello, I am in need of some post-production assistance. I am shooting a short on Kodak 250D, and am looking to alter the white balance of my captured images. However, I want to retain the color characteristics of the lenses and filters I am using in the shoot. I have the ability to detect the color temperature of the exterior lighting my film will be exposed to. Is there any way to adjust the color temp of my footage by an exact amount of kelvin? I.E.: Kodak 250d white balance is set at 5500k, my sunlight is coming in at 6200k. Is there a program that can alter color temp by an exact figure, rather than on a +100\-100 scale. I want to adjust the stock to be color balanced while retaining the color quality of the lenses and filters I am using.
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#2 Phil Rhodes

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Posted 12 July 2018 - 11:24 AM

Not precisely. The response of the film to light is not sufficiently linear for white balance changes to be made after the fact. You could do it more accurately by performing some sort of linearisation on the data. This would require an analysis of the film stock, processing and transfer, which is certainly posssible but probably nontrivial.

 

Many tools exist which will approximate white balance fixes after the fact, though they may not be very accurate.


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#3 Benjamin Kantor

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Posted 12 July 2018 - 03:46 PM

Adjusting Kelvin numerically with software or a plugin isn't super accurate or convenient, but the classic way to do what you're describing would be to shoot a gray card without your filtration in. This gives you perfect balance to whatever the daytime conditions are, and your filtration stacks properly on top of that.


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#4 Tyler Purcell

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Posted 12 July 2018 - 03:48 PM

Once the film has been shot, there is no more kelvin settings you can use in software. The transfer machine defines the color pallet and you'd then have to manually grade every scene after that. Using color charts with DaVinci does help keep color accuracy per scene, but only for base color balance, not for a particular look. Finding color balance is easy using the RGB waveform, so this step is unnecessary for film really. If you are looking to retain a particular look of a lens per say, that would have to be done in the grade. 

 

With digital shooting in RAW, you can adjust the kelvin in post production. 


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