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Green screen lighting set up nightmare....advice needed

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Christina Bulpett
Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 10:52:07 am

I have been charged with setting up a green screen studio but with very tight parameters and was hoping for some advice....


We have a small room/studio in which to set up a green screen, lights, camera and of course, presenter. The room is approx. 4.5 mtrs by 3.8mtrs, with a few awkward angles, corners, as it is not simply a rectangular area, that would be too easy!

I am shooting on sony Z5, with small canon Legria HF200 as secondary, and will edit on FCP with keylight plugin.

The lights currently owed are: Lowel pro-light, Rifa exchange88 and Rifa lite 44, Fluo-tec studio 450 and 250; a dedolight DLH4 and an Arri 650plus.


With the space and equipment owned, what is the best solution, is there one? Or should I consider options like Datavideo CKL-200 (CKL200) Dual Colour Light Ring & Retro Reflective Cloth or the Reflecmedia ChromaFlex / EL Bundles?

I am an editor, but my new company seem to think that I should also know everything about filming and lighting too!! Any help would be gratefully received.


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Mark Suszko
Re: Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 2:55:22 pm

My first question in trying to help is, can you get more "room" out of the room, so to speak, by taking the camera out thru the doorway, into the hallway or a second room? This may introduce some new audio problems, but getting the camera farther back opens up the tiny space you have so you have additional distance to separate the actor from the green and place the lights. The added distance also helps because if you can keep the depth of field shallow, the blurring this gives your green wall will help even it out more, improving the key later.

My rule of thumb for actor placement against greenscreens is they must stand at a distance of their height plus two or so feet away from the screen, to minimize color spill and shadow problems. Also, getting the camera out of the actual room means more room for the lighting gear.

Light the screen first, without anybody in the shot. You don't need to make it a dazzling, blinding neon green, what you want is EVEN lighting and decent color saturation, more than a lot of brightness. An over-bright green screen makes things harder, actually, by creating reflective spill and competing with levels on the actor. I like about an 80-percent IRE level on the scopes for my green as a starting point, as a rule of thumb.

The Rifas are what I use to light my green screens evenly. You might get away with using just the larger one on this job, but if not, just put them at the sides at 45 degree angles and go from there.

Hopefully, you have a hardware or software-based vectorscope/waveform monitor setup to analyze the green wall and see how even the lighting is. But if you don't have that, you can use the zebra bars function of your camera, coupled with manual iris control, to check for even lighting. Turn on the zebra indicators (those are the black and white stripes that appear in the viewfinder to show anywhere where the light is too bright and creating a "hot spot"). Slowly crank the iris open and closed, look at where the zebras start to pop up in the frame. You want the entire frame to pop into zebra at once, not just a hot spot here and there. Adjust the Rifa(s) until the zebras are uniform appearing and disappearing across the whole screen as you raise and lower the iris. Now you should be in good shape. Shoot a few minutes of this green wall by itself, just as extra insurance in post. Record audio "room tone" at the same time, again, for possible later use.

Leave that iris on manual now, turn off the greenscreen setup, and start lighting your talent with the remaining instruments to suit. Be sure not to let talent lighting spill onto the green. Remember to place your keylight so the apparent main illumination will match the angles in the replacement scene that will be inserted later. For example, if the replacement scene has the sun coming from camera right, put your key light camera-right as well. If you bring a sample of the background with you, as a still picture, while composing the lighting, you can match these things better. Turn everything on again with the talent in place this time, check to see if you added shadows or hot spots. "Roll tape! Er, Engage RAM!, Oh, whatever, record stuff! Action!"

By the way, why are you limited to *this* room, if you're doing green screen? If you're doing green, any location will do... Just something to think about. Sometimes you need a little "lateral thinking" in your life to be able to see extra possibilities.


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Alan Lloyd
Re: Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 7:52:13 pm

80 IRE is too hot for greenscreen, IMO.

I try to keep it in the 40-50 IRE range as a good compromise between luminance and saturation. At 80 saturation is beginning to fall off.

Here's an empty greenscreen (with WFM trace) I shot after a client piece a while back:



Note the even WFM trace, side-to-side. The bright narrow line is the luma, the wider one is the chroma saturation. There is a tiny bit of falloff in the corners on the left, not enough to cause any key trouble. And it's small enough and removed from the subject enough to be maskable in any case.

And here, with a subject in front of it:



Here's the finished key, using a BG that was not part of the actual client piece, just grabbed for illustration purposes:



That was done using only the chromakeyer in Premiere Pro with a straight DV capture. No additional tricks or manipulation were used.


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Mark Suszko
Re: Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 8:41:19 pm

Well, I *did* say " 80 IRE as a starting point"; I could go lower, depending on the rest of the shot. But 80 is what seems to work pretty well in our shop, under our particular conditions, your mileage may vary, etc.

That's a nice example you put up, though I see an area at and under the ears/around the jawline/cheeks where it needs a little more spill cancellation or choking, but if that was my initial shot upon activating the keyer, without and before any further adjustments or tweaks, I would be very impressed and happy.

Kids today really are spoiled when it comes to keying ability; it used to be way harder back in the day.


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Mark Suszko
Re: Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 8:43:23 pm

I do agree with Alan though that the saturation is more important than the luminance, and of course being even all the way across in any case.


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Alan Lloyd
Re: Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 8:49:45 pm

Now I'm going to want to go back and mess with a months-old project just to see if I can tweak it even closer.

Thanks Mark, enjoy YOUR weekend!

(truly evil grin)


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Mark Suszko
Re: Green screen lighting set up nightmare....advice needed
on Jul 2, 2010 at 9:05:23 pm

Oh YOU have that same OCD curse as me... :-) For the dedicated artist, a work is never truly finished, you just run out of time and have to abandon it at some point and go on from there.

And yes, it IS kind of a dirty trick to point out a co-worker's little error here or there, but I look at it this way: if I had spinach in my teeth, or my fly open, or something like that, I would want my real friend to tell me first, and not leave a bro hanging all day.

(you got a little... thing there... no, the other side.....)


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Alan Lloyd
Re: Green screen lighting set up nightmare....advice needed
on Jul 3, 2010 at 11:25:53 pm

Yeah - OCD to be sure.

The real client piece I fussed more with, of course, and it was over a better background in the bargain.

Using regular tungsten on the greenscreen, I've normally put white silk on to spread the beams out and make the lighting on the BG a taste more even. Works well, and I'm generally happy with the results.

Maybe if the edge light on the subject had been just a bit more "butch" the key would have been bang-on right out of the box. And if he'd been willing to take a bit of powder to knock down those forehead pings...

See what you started?


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Mark Suszko
Re: Green screen lighting set up nightmare....advice needed
on Jul 3, 2010 at 11:33:07 pm

You know, everyone's in love with using green these days, but the thing about using blue is, on many kinds of backgrounds, it lets you get away with a little more if there happens to be some spill or whatever. Blue is a more commonly seen color in background plates than digital green, and sometimes it just blends and works out okay even if less than perfect. I happen to think keys done off blue can be a little more forgiving in the final composites.


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Dennis Size
Re: Green screen lighting set up nightmare....advice needed
on Jul 4, 2010 at 1:01:45 am

Is this the way the subject actually looked?

DS



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Alan Lloyd
Re: Green screen lighting set up nightmare....advice needed
on Jul 4, 2010 at 4:38:49 pm

In fact, it is. A divisional VP, the guy was. Rumpled, shiny, kind of frown-y, and came in with his corporate group - including a very senior marketing person. No makeup - didn't want any. They just wanted to get the recording done and out with his PPT slides over much of it.

They were the client of my client. I was far enough downstream to not be given a great deal of input.



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