S Log Zebras & Exposure

T

Tony Brennan

Member
I've notice that the in built LUTs change the zebra readings and brightness meter readings in the camera viewfinder and LCD screen. If you are using the LUTs for preview to client monitors and were relying on the cameras internal metering it would give you an incorrect reading of the S Log exposure. The metering is reading the LUT image not the S log image. How do you send clients a LUT feed, but expose the S log correctly at the camera? Even external waveforms monitors would need to take a feed from the 444 feed, not the 422 SDI feed as it will only give you exposure info for the LUT image not the full S log image. For example a white area that is reading 80% in S log will read 105% with a 709 (180%) LUT applied or mid gray @ 35 will read 41 with the LUT. Any ideas?
 
The histogram is also affected. The obvious solution is to apply the LUT in the monitor and not the camera. That can be an added expense.

Would it do any good to reset the zebra levels? If you normally keep white skin at 70, to drop it down to 60.

Have you tried any other solutions?
 
White skin should be @ 40-45IRE in SLOG

The F3 only goes as low as 50 on the zebra.
 
Well... IRE is not same as a percentage, but I understand you're saying it won't go low enough.

Haven't played with it yet, but Timur are you then using the HG8009G40 setting? (18% gray at 40 IRE)
 
Zebras at 50% = 50 IRE. 100%=100IRE.

The % goes up to 105% in the F3, representing the clipping point.

i use no lut, and a waveform.
 
TimurCivan said:
Zebras at 50% = 50 IRE. 100%=100IRE.

The % goes up to 105% in the F3, representing the clipping point.
Click to expand...

Since the full stop range is 9 stops (if you consider 1.4, 2.0, 2.8, 4, 5.6, 8, 11, 16, 22) or 11% each. Then, as a field expedient practical matter can I set zebras for 50%, expose for white skin to hint at zebras, and then take it a full stop down with a ND.3 filter? (I don't have a waveform and the histogram is inaccurate for this.)
 
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Do you have a monitor with false color? You have to get a more accurate method of exposure.
 
No. Stupid me bought the TVlogic without the extra functions like false color and waveform. I didn't like false color much on other people's monitors and didn't think I'd need it. I do miss the waveform though. Arrrgh.
 
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