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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Shooting Green Screen experience and suggestions.

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BigLu

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I direct this question towards DoP's and compositors who have shot with this camera next to a DoP.

This is not my first time shooting a Green screen with RED.
14 music videos
and a feature all green screen, I just want to get better.

So im not looking for basic input, instead I would like to just hear some of your suggestions and any experiences that you've had with green screen in a more optimal quality level.

Directly:
What ISO do you prefer to set the RED at
What T Stop do you ideally like on the camera
What do you light your talent at Tstop at
What do you light your Green Screen Tstop at of F-stops at for those of you who use F-stops terminology.

Even lighting is a given, soft lighting is a given.

No doubt the camera likes to see daylight out doors / HMI lighting or even daylight gel color corrected tungsten lights.
I can't go HMI so id like to hear what would you choose between
Daylight gel of all your tungsten lights or do you opt to go with an 80C or 80D filter in front of the lens.

Are there any keying advantages of shooting 4K vs 3K or 2K.
I am transcoding to 1080P DNxHD 10bit
I don't care that i can take advantage of punching in when shooting 4K or 3K for this particular project.
I have not tested this yet in the field but maybe someone else has.

Green screen stage is 45ft by 70ft

Any suggestions would be appreciated.
Thanks
Luis
 
Hi Luis,

The biggest thing I have found, is to give the VFX guy what he/she wants. For example, I did a green screen shoot where the VFX guy was on set, and I got away with shit I never would have otherwise. If you can talk before hand about what specific programs are going to be used, and what they require. 2 different FX guys may have 2 totally different requirements. There is no one size fits all solution.

Nick
 
Love that suggestion Nick big time.
Problem is they are in another country around the world and thats not going to happen for me.

But to say 2 different FX guys may have 2 totally different requirements is spot on.
I agree 100%
I guess i look forward to some guys ideas.
The more ideas and input i hear the better ill feel.
Its RED so hearing what guys do specifically when it comes to RED is kinda cool.

Thank you Nick.
 
Using the RED I set camera ISO to 320. I set the meter at and light for 250. Adjust for any filtration on the lens.

In other words its a RED, and I don't alter how I use it just because its green screen. Green screens work fine at any aperture needed for the scene, and for any camera/film stock.

If the green screen must be tracked, you might want to work a bit to set the lighting&stop so it can be in focus. Otherwise use whatever aperture you please. If its out of focus that generally helps with any imperfections in the screen and helps smooth out lighting.

In my experience, lighting is the key to green screen success. Its also simpler, at least in concept, than people think. Implementation can be a bitch sometimes, but remember the concepts are very simple. Get too fancy and you will bite yourself in the rear.

I expect that a lot of what I have to say, you already know.

The main thing with green screen, I make sure its at least one stop over key and as uniform as I can. (Sometimes that isn't very uniform). If I get it bright enough, I can later pull either a chroma green key or a luma key.

I also like to take the time and build in separate lighting rigs for the screen and the talent. I like to light the screen first, then measure its contribution (i.e. its candle "output" ) at the subject positions. Then I start the lighting for the subjects by setting the hairlight as bright as I can justify in the scene. The objective here is to defeat the spill from the screen as best possible.

At the subject I want the hairlight to deliver at least four times the candles as the green screen does.

This notion is the basic idea behind keeping your subjects away from the screen. Limit the contribution of the spill to your total lighting, then defeat it as completely as you can with lighting.

On a recent RED shoot the green screen was 3 stops over key and reflecting 8 candles at 20 feet.(~86 lux at 6.1 meters) I was shooting for t/2.8, which is 40 candles. I used 72 candles for the hairlight after compensation for a little minus green (1/8 I think, would have to check with the gaffer) to balance out the light/color contribution from the reflection. Spill was a non-issue on that setup.

I don't think any of that is mind-bogglingly hard or subtle. I hope it helps.
 
I've only really supervised on one set with RED, but this is the one major piece of advice I would give.

On earlier builds I would say 2K was too soft and noisy to pull a great clean key from if you were finishing back to HD or higher res - so unless you absolutely need to crank the high speed then stay away from 2K and definitely use 3K where it can suffice.

Not that it can't be done, but 3K and 4K are REALLY friends of the VFX artist in this particular arena.

I presume that you are mastering out to HD DNxHD and the VFX guys will never see the original R3D's, in which case I would suggest 2K becomes even more problematic as they won't be able to tweak it the R3D's to get the best out of them and they'll just go through RED RUSHES like everything else, so that would be another strike against 2K if you can avoid it (perhaps, if you can't avoid it, you could also supply the original R3D's of just the 2K stuff is space allows - just so that they have those shots to go back to in original format.?)

The project we did had a lot of punching in and cropping in post, and if the VFX guys are having to punch in to the DNxHD after you have transcoded them then they are going to be worse off, so obviously frame so you give them as much resolution around the subject as possible (including tilting the camera 90 degrees on tall thing subject matter surrounded by green, the additional resolution REALLY will help, ESPECIALLY if you are transcoding down to HD.)

I let the DOP's talk about the lighting issues.
 
Thanks Craig,
I wish i could get them to go back to the R3D but i cant.
So I will do my very best to get them to shoot perfect.

appreciate it.
Luis
 
Alexander thank you I will test pumping up the light on the hair i like that suggestion.

Luis
 
I'm going to leave specific camera questions to others, but since I have both an effects and a production company and shoot a lot of Greenscreen, I figured I'd chime in with what I think matters most.

I think the main thing to address first is know if you're trying to blend into a scene or if you're trying make something pop (like a human on a graphics background). If you're trying to blend into a scene, then must serve all your lighting purposes to that end and the biggest thing you'll do to help your visfx artist sell the shot is to get the lighting matching right. It's something people pick up on very well and something that darned near impossible to convincingly fake in post. sometimes people will say add light to the edges of the bodies to control spill and such... that often just makes your character stand out and never blend in which is exactly what you don't want in a blending scene. In the graphics / stand out version, it's fine.

Make sure your talent is far away from the screen and black out EVERYTHING Green you don't need. These help most. Spill is the thing that sucks. Watch for anything that is reflecting green onto you talent - especially on the edges.

I'd shoot 4k.

Remember that yellow is often edging on green and khaki is green as far as keyers are concerned when things get tricky.

If you want some other thoughts on visual effects, creative cow asked me some questions on our work process when we improvise visual effects (which we do often) and the online version of the article is here:

http://magazine.creativecow.net/article/improvising-visual-effects

I forget if I talked much about Green screen in there or not at this point, it might ahve been an earlier article. But it might be interesting in the investigation.

By the way - one last phenomenon I thought was interesting and I don't ahve a solution, but we once shot American Idol's Allison on Green Screen and she has solid red hair and you'd think it'd key perfectly. No. It was the weirdest thing which I suppose made sense after thinking about it, but the keyer would not do an easy key on the hair because as it blended into the bg, it blended into the green (which was sort of a white by the time the green was out) and she had this crazy rim. solution was to garbage matte the edges and then manually hue the outside hair to match the rest. Looked fine in the end, but it was a really odd technical experience to face.
 
Mark Allen said:
sometimes people will say add light to the edges of the bodies to control spill and such... that often just makes your character stand out and never blend in which is exactly what you don't want in a blending scene. In the graphics / stand out version, it's fine.

Make sure your talent is far away from the screen and black out EVERYTHING Green you don't need. These help most.
Click to expand...

Couldn't agree more. Don't use magenta to try to kill spill, you end up having one more color to spillsupress. Try to block it out with black instead.
 
I haven't used it myself yet, but Keylight (plugin for FCP) is supposed to be very good. The keying tools in most editors (and FCP) are pretty basic. Keylight takes everything a monumental step further and can help "rescue" bad setups and make adequate setups look extremely good. I am not affiliate with them in anyway either! They also have some PDF case studies from recentmovies, such as Sweeney Todd etc. The basic single user, single machine permanent licence only costs $250. If you are serious about green-screen work, this appears t be the way to go. Here is some info taken off the website (www.thefoundry.co.uk)

"Keylight is an industry-proven blue/green screen keyer. The core algorithm was written by the Computer Film Company and has been refined on scores of films. It is simple to use and is particularly good at tackling reflections, motion blur, semi-transparent areas and hair. Because spill suppression is built-in, often selecting the screen colour is all you need to do to pull the matte and key the foreground into the background so it looks photographed rather than composited.

Keylight comes with a suite of tools to erode, soften, despot and otherwise manipulate the matte should the need arise. Inside and outside matte inputs are supported. Separate colour correction, suppression and edge correction tools are also included to fine tune the result.

Keylight has an unparalleled pedigree, having been used on scores of feature films including: Wanted, Speed Racer, Sunshine, Sweeney Todd, King Kong, Charlie and the Chocolate Factory, the Harry Potter series, Mission Impossible, Resident Evil, Sleepy Hollow, Chicken Run, The Truman Show, Armageddon and many, many more.
 
Agreed with Julian
 
Apologies for my somewhat incoherent typing. My kids recently spilled apple juice on the cruddy old laptop we use for internet access (having crddy old laptop for internet access when you have kids is a very good idea it seems!!). A lot of the keys are sticking or not firing properly, turning my usually coherent word flow into what appears to be the rantings of a demented loon.
 
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