Chroma Key for RED ONE

[Jason Weitz]

Simple(?) question: Is there anything specific about the RED that would make one chroma color superior to another, in other words, green screen or blue screen, which is best for the particulars of the RED?

[Reinhold R.]

From what I've heard RED works better with green screen since the blue channel tends to get quite noisy under insufficient lighting conditions. So, either use a well lit (daylight) blue screen or a green screen.

I don't know at which color temperature a green screen should be lit though but my intuition tells me that tungsten should work better in that case.

[martinnoweck]

if you type "greenscreen" and press "Search" there is possibility to find the following thread:

http://reduser.net/forum/showthread.php?t=27571&highlight=Greenscreen

i did a greenscreen job last week and daylight worked best. (using keylight in after effects)

regards ;-)
martin

[Frank Martin]

we have shot a ton of greenscreen
and daylight balanced lighting/kehlight
works fantastic don't be afraid to add
Blue at camera 80c/80d if you are stuck
with tungsten lighting.

[Lewis-M Soucy]

Does CTB do the trick instead of 80c or d ?

[Eirik Tyrihjel]

Does CTB do the trick instead of 80c or d ?

According to some tests I have been allowed to look at, the 80c will take away almost a stop to do it´s correction (it was designed for film - not digital), while the 1/2 CTB will do pretty much the same correction but only take away 1/3 of a stop...

[Jan Balster]

Go fxPhd.com and look in their fxPhd TV archive for RED and green screen. They went pretty in-depth on the whole tungsten vs. daylight question and have some nice side-by-side comparisons.

Good luck.

- Jan

[Frank Cueto]

In post you might also want to output two sets of files (preferably after offlining) from ur R3D's.
One set where u only grade with primaries and no OLPF, this set you would use to generate your matte, and the second set with olpf and any CC you might fancy which you can cutout using the matte you generated from the normal looking version of the footage.

We just finished a project where we gave red post support to a localvfx studio and we followed a similar approach. Only difference was that we gave them the GS Footage with only primary grading correction, afterwards they returned the footage already composited and an alpha channel of the matte they pulled.
This allowed the director to tweak the final composites realtime on our baselight suite. A very nifty experience indeed.

Frank Cueto
Reaktor Post & Transfer
San Juan, Puerto Rico

[BradWright]

Make sure you have way more light on the set than you need. Add lots of fill light on dark hair or objects to get above the noise level in the camera. Get at much light on the scene as possible, so you prevent problems in post. You can crush the blacks a bit in post, but getting rid of noise is nightmare.

If you can have scopes on the set and pre-visualize the key.

[Stephen Williams]

Make sure you have way more light on the set than you need. Add lots of fill light on dark hair or objects to get above the noise level in the camera. Get at much light on the scene as possible, so you prevent problems in post. You can crush the blacks a bit in post, but getting rid of noise is nightmare.

If you can have scopes on the set and pre-visualize the key.

What if you want moody lighting to match your background?

[BradWright]

What if you want moody lighting to match your background?

The big mistake I made when I shot chroma key with the red is under lighting. I think it's really important to get attach a waveform monitor to the camera and look for the jitter that is caused by noise. It's easer to push the blacks down in post, than it is to get noise out of video that is too dark.

I'm seriously considering adding a bunch of noise detection tools to Veescope Live in order to handle this issue. It's crucial to blast the sensor with enough photons to get above the low level noise. Otherwise, you get grainy edges that break up randomly in post.