FS7: R Black / B Black Level

K

karma17

Well-known member
Good day.

I've seen where some like to adjust the Black Level Master any where -2 thru -5 or so for richer blacks, but I was curious when you would adjust R Black and B Black. From what I can gather, these are adjustments for the Black Levels on the Red and Blue Channels individually, but why no Green channel then? I know in color correction programs you can pull down black levels in each channel individually and this seems to be the same sort of functionality. I am just trying to understand a bit more of what's going on under the hood.

Thanks.
 
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There's no reason to adjust the R Black and B Black levels unless your camera is malfunctioning. Blacks needs to have no color tint. If there is a color tint and the blacks aren't neutral then you could use R Black and B Black to compensate. Green is not needed. But before you do that, Black Balancing the camera ought to fix any problems instantly. I black balance my cameras every month or whenever they ask for APR. Some controls on the camera just need to be left alone.
 
While black balancing the camera 'should' take care of adjusting the black levels, when doing multi-camera shoots small tweaks may occasionally be called for - even sometimes when all cameras are the same model. It's good to have the adjustments available if you need them! (Obviously the adjustments are made in conjunction with a waveform/vectorscope). For single-camera shoots you probably won't need to do anything more than a black balance.
 
+1 on Doug's reply. R & B blacks are there for alignment. With most of today's digital cameras their levels accuracy is pretty well spot on and if all is good leave well alone. With the master Black level yes if you want more "crunch" in you blacks you can knock that down to -3 to -5 but be very wary around -5 as that level is sitting right on the blanking and any lower than that you are introducing vision below Black level. Definitely a no, no. Also second DJ's black balance practice.

In extreme hot weather shooting black levels can drift so again worth doing a black balance in those situations where the camera can get very hot. Shooting out here in 48-49 Celsius conditions sometimes we can see the blacks lift a bit. Once upon a time with analogue circuit cameras it was also common practice to black balance if you had to use gain but these days I don't really see much need to do it with modern digital processors.

Chris Young
 
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