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900R Preset White Balance


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#1 Jerry Doran

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Posted 29 November 2007 - 12:00 PM

I was doing a shoot with a 900R in daylight with a few HMIs. We switched in the daylight filter using preset white balance and the image turned a deep orange. We ended up using the 4300K filter, but even that was too warm...so we ended up taking it out of preset white and manually dialing in the white balance. When we finally achieved a correct looking image, the color temperature in the viewfinder said something like 3900K, several thousand degrees Kelvin away from the actual color temperature. Has anyone experienced similar difficulties with preset white balances in the 900R?
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#2 David Mullen ASC

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Posted 29 November 2007 - 12:11 PM

It sounds like you had the WB switch in the A or B position rather than PRST (preset). In PRST, the camera basically goes for a 3200K balance and uses the filter wheels to color-correct, so the RGB gain levels are all at "0".

But if you are in A or B, there is already some leftover white balance being stored, and the filters will end up coloring that as a starting point. Of course, you can use that as a trick to get certain affects, for example, white balancing with the camera using the "C" filter (sort of a halfway correction like an 81EF) outdoors so that "C" becomes neutral in daylight, and then switching to "D" (or "A" if that is an 85 filter instead of a cross filter) for a partial warming effect.

I suppose it's also possible that someone monkeyed around with your Color Matrix...
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#3 Stephen Williams

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Posted 29 November 2007 - 04:02 PM

It sounds like you had the WB switch in the A or B position rather than PRST (preset). In PRST, the camera basically goes for a 3200K balance and uses the filter wheels to color-correct, so the RGB gain levels are all at "0".


Hi David,

It's quite possible to reset PRST, so they can never be guaranteed. It's just a white balance somebody did in the engineering settings.

Stephen
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