Green Screen question

[Ed_Scott]

I'll admit it that I really do not have much experience shooting with a green screen. Any tips on how to do it right?

[Run 'n' Get 'em]

Make sure there are very little to no shadows on the green...

[cameragod]

Ok so the first thing is what are you shooting on? DV and green screen is not a good match. Almost any other format is better. Second get as much distance between the subject and the screen as you can to prevent shadows or spill from the subjects lights on the green screen and to stop green light bouncing back onto the subject.
Lighting the green screen is everything. It needs to be an even soft light. 4’ Fluro’s are best but at a pinch a Blond bounced off a white foam board on either side can work wonders as long as you can flag them off the subject.
One trick I do when setting up is to slightly over expose on the green screen then turn on the zebras and try to get them constant in the viewfinder across the green screen. That way when I properly expose on the subject the green screen with be slightly under and easier to pull a key off.
A hard backlight on the subject can help and a pink tinged gel (amber for blue screen) sometimes works depending on the software being used.


My top tip is give yourself plenty of setup time. Get the lighting right and the rest is easy. For me green screen days are usually an hour of lighting bliss followed by a day of total tedium.

[Ed_Scott]

Thanks for the input. I'm shooting on my Varicam. Now this could get interesting cause Panasonic actually has a setting for Green Screen. I'll load the setting and see. At this point, I'm not sure what we are shooting, but we will be in a studio and we do have plenty of time to light.

[Nino]

It’s been a real long time for me since I’ve done any chromakey set-up. I can tell you what I know (shouldn’t take long).
This is probably what everybody knows.

The elelmentary thing that everybody forget. Make sure that the subjects do not wear any clothes of the same color as the background. Also blue or green eyes might give you problems, depending of course if you use blue or green screen.

In lighting the subjects (the Ultimatte analog days) we used a slight lighting separation (back and rim lights) with some gel (1/4 should do it) of the complementary color of the background, magenta for green and yellow for blue.

Keep your subjects good distance for the background to eliminate shadows and to prevent the green (or blue) from bouncing back into the subjects.

Light the background evenly, very evenly

Make sure that the lighting directions on the subject match the lighting direction on the chroma images of the background footage.

I know that there’s an optimal IRE brightness for lighting the chromakey background. I knew it but that was long ago. I know if too bright or too dark it might give you problems.

If you check on my demo page and scroll down to the Jose Cuervo marketing piece. The whole thing was shot in front of a blue wall that we painted with Rosco Chroma Paint. That was a while ago.

http://www.nino-g.com/demos.html

[Hiding Under Here]

Scott:

I shot recently using a green screen background. Luckily I had a good lighting guy working with me. He had had a lot of experience working with green screen. It's pretty difficult to screw it up.

Just light the green as evenly as you can. Make sure that the green doesn't reflect back on your subject. If you are using a smallish screen, you can even shoot some of the frame without the green screen in it as long as your subject (I am assuming it is a person/head shot) has green surrounding their body. The rest doesn't matter all that much because they can piecemeal in the green in post.

When you aree done, shoot a longish shot of just the green. That way you can use it in post to fix spots where you might have had to shoot off the green screen in order to make your shot. So, if you have enough green screen for the height of the frame (for example), but the screen is too small to cover the width, as long as your subject is surrounded by green, you're okay. Use the shot that is a frame filled with green to fill the holes later in post.

We borught along a switcher with a chroma key function to check the shot. But that's hardly neccessary. Just light the screen evenly. Give your subject a good edge light. Make sure they have green all around the areas that need to be keyed. You'll be okay.

[freedom]

I've only been doing chroma key work for about 18 years but I'll give you my 2 cents anyway.

I've had several gaffers fight me initally on my method of lighting green. I light the subject first. I don't give a Flying F about the BG, the subject is important. I place the key light, the back light, the fill light, the edge light, the hair lights and everything else I want where I want them, THEN I place my BG lights where there is a need and a space left. I find that there is plenty of spill from soft key lights hitting the green of a typical portrait so I usually only need a tweenie to suppliment and even out the BG.
And, BG's don't need to be so precisely even as they used to be back in the day where 1/3 stop diff caused great knashing of teeth from the edit bay.

I was called in to reshoot a piece for a big deal DP from Hollywood back in '92 who screwed up the key something fierce. Shooting on 35mm, he totally overexposed the BG, according to the gaffer. Client paced around like an expectant father at the reshoot. Editor reported directly to me that it was perfect, took him less than 5 minutes to dial it in. We had a car in the shot with reflective surfaces. I won't go into that whole bag of tricks but if you are shooting anything reflective, have fun!

I did a series of 12 keyed portraits and sure enough the 11th guy shows up in a light green shirt. Client acknowledges it and says 'give it a shot'. I dropped the BG from 60 units to 40 units. The light green now had a pretty strong difference but the shadow under the collar was quite close to the BG. Editors report was that it didn't take much at all to dial that out. They can really pick a very tight vector. In this case, even BG is important but if there's no green in the subject then you can be a 1/2 stop off with no issues, unless the keyer is some old antique or highly compressed. Since you are shooting Varicam, you should have no issues with 1/2 stop variation.

[2000lux]

I do a lot of portable green screen shoots for a client on HDV. Mainly they are interviews. While I like the idea of Freedom's method better, I rarely have much time (or room) to light the "set." It helps a lot to have a wave form monitor handy. We use the DV rack program. My clients don't have the greatest light kit for this. I'm told a couple of Chimeras work well. I usually have an Omni and a Tota with some opal diffusion on the Omni. Generally we're traveling with their gear so I'm stuck with it.

First I frame up the shot so I know which part of the screen I really have to focus on. I place the subject's chair about ten feet from the screen or so (as was said before, you want to avoid shadows on the screen). Then I set up the BG lights, preferably about head hight, on either side of the screen and set the iris so that I just get a narrow line on the wave form at about 55 IRE. This usually requires some tweaking of the position of the lights once I've set the iris. After that's all set I flag off the light that will spill on to the subject (I just use some blackwrap and or the reflector).

Then I light the subject. Usually with a Riffa for the key, a Pro Light for a hair light (generally on a stand behind the screen) and a reflector for fill. I leave the iris set and just adjust the subject's lights (mainly just by moving the key in and out and tweaking the reflector) to make sure the exposure is right.

I know it's not the most elegant lighting set up but it works.

[joecam147]

Ok, thats one way or several ways to do it. The easiest way to accomplish green/blue screen for heads and bodies or larger depending on the size of your background is to find a Reflecmedia Chromflex for rent. Park it on your lens, fire it up and adjust the effect and you're done. You only need to light your subject, NOT the background. Check it out.
http://www.reflecmedia.com/
I've used this for over four years on a cable series with no problems. Your editor may need a plugin if you're cutting on an Avid or FCP but chances are they already have what they need to tweak it.
No worries with spill or different color temps and once you have it down it can be up and ready in twenty minutes with time for coffee and you are the hero.
Apparently they do not advertise because it appears nobody else knows about it, at least I have not crossed one yet but for Blue/Green screen its the way to go.
If you are interested and cannot find one for rent contact me
directly and I'll rent you mine.
Yes, I was so impressed I bought one, didn't everybody go through the greenscreen stage about a year or two ago when everybody was doin' it ?

[freedom]

joecam
How much did this cost? I saw it demo'd when it first came out many years ago but it's always the money.
I get $35 for my ultimatte 12' X 14'. How much extra does your system rent for vs. saving a half hour in setup?