Red one vs Epic 4k green screen?

[Björn Benckert]

I have a quick question. But first som background.

We are working on a 4k feature where we have a 7 minute long shot with quite large greenscreen. We have done tests and the film team have been rehearsing this sceen and setup for months... and it's quite a prestigious project. The scene is setup with a RED One MX and now when keying on the test material in 2k I find it to be more "mosaic like" than footage from our epic.

So how big is the difference in the best compression setting of the RED ONE compared to epic 4k 3:1?

I do not want to ask them to change camera if there is no difference. But I guess the RED ONE with one of those cradle disks can not do 3:1, or?
Is there also other differences in how the material is processed?

Just figure I could ask here before starting to swap camera etc.

The whole scenery is built around 4k sensor and a 16mm ultra prime so I can not go to 5k...

Quick answers would be great help.. I have a meeting tomorrow morning with producer and director.

 

[Mark Britton]

The RED One can't do the equivalent of 3:1 compression ratio in Epic terms.

On RED One, converting REDCODE numbers to compression ratios ala Epic:

REDCODE36 similar to 8:1
REDCODE42 similar to 7:1.

 

[Björn Benckert]

Thanks Mark, So if understand you correctly... The best I can get out if RED one is about twice the amount of compression as i get out of my epic at 3:1, correct?

Then there is definitely an improvment to Epic for the real shoot. Is it also less noise? I mean since the processing is all different? I never really shot them both 4k side by side same shot same lens, etc. so I have no testing of my own to go by.

My guess epic is better even on the noise...

Decisions, decisions...

 

[Stephen Williams]

I did some destruction green screen testing about a year ago on 1.6.9.
I found using 5:1 was the maxamium compression that worked in darker areas, above that there were issues. All the screen work I have done since has been at 5:1 or less.

 

[John Marchant]

EPIC is cleaner and far less compressed - for a prestigious 4k format shot with chromakey I'd be maxing out the compression slider without a question. Worlds apart from the best Red One can do.

Bear in mind that iirc Red One to raid drives will only do RC36 at 4K16:9 - you need to pinch down to 4kHD for RC42, and that might not work for your optical calculations.

 

[Bob Gruen]

What exactly does "keying on the test material in 2k" mean?

Are you shooting 4K and transcoding to another CODEC in 2K then keying, or are you shooting 2K R3Ds and keying from them? If you have had this much time with a greenscreen to get it set up and tested you should be able to shoot with a R1MX with no problems. What software are you keying with?

Ive done a fair amount of keying in Ae with various delivered keyers and after-market plug-ins and have had very little problems with keying R1 footage as long as the screen is properly illuminated. It is a 10 bit 4:4:4 data stream that the keying software works on. The compression ratio of the R3D just goes to the fine detail adjustments and really wouldn't cause any blocky-ness. Think of the compression ratio as adding very minor rounding errors on a set of mathmatical equations that are designed to return a large amount of black and white with fine details in the shades of grey in between. A color that is not anywhere near perfect green should exhibit no artifacts at all.

Bob