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-   -   Black blacks (https://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/487060-black-blacks.html)

Bob Grant November 5th, 2010 07:16 PM

Black blacks
 
I had an EX camera hooked up to a Panny monitor yesterday and looking at the waveform monitor I found it was impossible to get absolute black, even with the lens hood and iris closed. Changing Black in the PP to -5 to -10 solved the problem. I had a dead straight line with no dancing noise.
Opening the lens hood and iris I didn't notice any harm being done to the image. That is a based on a very quick eyeball though.
I typically do the exact same thing in post to reduce the noise level and save bandwidth for whatever I'm encoding to, doing the same in camera to save bandwidth seems logical enough to me. Anyone think of a reason why I should not leave Black set at -5?

Piotr Wozniacki November 6th, 2010 03:45 AM

Bob,

Based on the same observations/experience, I've had all my PP's with negative Black levels since the very early days of using my EX1. The exact value depends on the Gamma curve used in a given PP, but it usually is in the same range of -5 down to -10.

Piotr

Bob Grant November 6th, 2010 06:37 AM

Thanks Piotr.
In the past I've wound black gamma down a bit to push the noise down. Next time I have to shoot a lot of black I'll try the alternative of dialing Black down a bit.

Leonard Levy November 7th, 2010 01:23 AM

It may vary with the gamma you're using, but I've had my black at -6 ever since I got the EX-1. I use standard gamma 3. I don't know why they set 0 so high. The HVX did that also. On the HVX if you were shooting with 7.5 set up added, I think black at 0 was correct at 7.5, but if you went to 0 set-up, the Black would only go down to 5 IRE or so. Thus I also ran my blacks somewhere from -4 to -6.

I think that should be the correct way to shoot for maximum tonal values and bandwidth. You don't actually gain any information if you run the black higher, you just wash out the picture. If you want to gain grey scale down there do it with the black stretch or black gain - whatever they call it. Black should be black and that's around -5 or -6.

David Issko November 8th, 2010 02:09 PM

Quote:

Originally Posted by Bob Grant (Post 1585360)
Changing Black in the PP to -5 to -10 solved the problem. Anyone think of a reason why I should not leave Black set at -5?

Bob,

Checking & adjusting the black levels on my EX3 & PMW-350 was one of first things I did to my cameras. Both needed to be set down a little to the same waveform setting as you have. Not sure of the numbers but -3 to -5 rings a bell.

I have kept them there ever since and periodic checks reveal that they are sitting nicely at those settings.

I have never encountered any issues with either camera since adjusting the settings downwards.
Cheers

Olof Ekbergh November 8th, 2010 03:17 PM

On cinegamma 4 my standard settings are:
Black -3
Black Gamma -2

I also set detail to -10

I think all cameras need some dialing in. Scopes and good calibrated monitors makes this much easier. Modern eval monitors now come with scopes included a real money saver.


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