Thread: Black is not black
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09-19-2008, 12:52 PM
When I cover the lens and take a shot - and then output a tiff from RedCine the black is 10,10,10. Is this as it should be and if so can someone explain why.
I am new to filming but in my animation I make sure black is 0,0,0.
If there is a way of setting black to black I can't find it.
John Redfern
09-19-2008, 01:00 PM
Have you tried setting the black levels in the camera? There's an option to do this..check the manual.
09-19-2008, 03:23 PM
RED is almost always corrected in post. As I understand it, black is elevated so the camera never clips shadow information.Originally Posted by JRTT
You should be able to test REC709 vs REDSPACE and use the in camera looks to drop the black level. Also, try turning off dark detail.
09-19-2008, 04:45 PM
I would suggest adding a digital ultra-con filter to your animation clip to achieve more "film-like" blacks to match the RED's.
Just kidding!
:clown2:
09-19-2008, 05:10 PM
Joelnet, can you explain on how playing with the dark detail will affect black level? According to manual and tests, changing black detail will only "light" up the shadow to allow one to see and not actually do anything to the captured image if nothing is done to the iris or lighting. Lim
09-19-2008, 05:15 PM
There is no inherent curve in the camera.
In a "normal" [think F900] camera, there is an inherent curve which crushes data below a certain noise floor to black. So rather than the signal just eating the noise, the camera takes its sensor data and curves the bottom end to a true black before compressing it.
The RED captures RAW data, so there is no inherent curve in that regard. As a result, the darkest point of an image is not black - instead it is where the noise becomes so great that it eats the signal.
If you put the lens cap on and look at the histogram, you'll see a big spike just to the right of the left of the histogram. The left of the histogram is black. Since RED doesn't have a true black, all of the darkest points [where the noise has eaten the signal] is just a bit to the right [aka brighter] of black.
Long story short: it's black. Curve the image, crush the blacks a bit and see where it gets your values.
09-19-2008, 05:29 PM
I didn't know if that option would effect metadata or not so that's why I thought playing with it might show a difference. I've never tried it... I guess that's why I used the words "try" and "might" and stuff like that.
The reality is as Brook states. The camera records raw, everything in camera is metadata and I always end up tweaking in post - but theoretically in camera metadata changes might get your blacks to zero. I just don't know. It's no big deal unless you really plan on a workflow where there literally is no color correction anywhere in post.
09-19-2008, 05:34 PM
Joelnet. thanks, just wonder if anyone uses the dark detail feature. Lim
09-19-2008, 07:35 PM
We put the blacks level above zero so we don't clip anything arbitrarily.
09-20-2008, 04:21 AM
For certain work - specifically, shooting miniature automaton birds with very bright green and blue feathers - blue or green background keys are useless and I have developed a technique of creating a pure black background to film against. In the brightly lit bird all shadows are well above black and I get a perfect key - even through the feather edges.
So to have black absolute is good in this situation. Black Shading seems to reset the factory defaults which as Deanan says is just above zero.
As long as there is a decent ramp between my black black and the other shadows I should still be able to get key. But it would be nice on occasions to say black is black.
John
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