LED For Lighting GreenScreen?

R

Robertofish

New member
I was wondering about LED Lighting for Green Screen, and if its a good idea or bad idea, heres the situation, the studio I will be placing the greenscreen in is 17x16x8 feet 8 feet being how tall it is, so I don't have a lot of room, ideally I would like to hang lights down that way they don't get in the way, we will be using it as an editing room and other things to, so we will be doing wiring via the ceiling that way there is no cables on the floor, we will be running as long of cables as we have to and keeping all the lights and things we use on the ceiling area, and we will be keeping the greenscreen there 24/7, so I was wondering given the space only 8 feet tall, I was thinking LEDs would be the best given the situation because of their usually small size as compared to these huge florescent banks and what have you, I also would like each light to be dimmable in some way, that way if one lights to bright we lower it, now the space we will be working with is just an 8 foot by 8 foot green screen with 4-6 feet on the floor, so its not like given the size of the green screen we need extremely high end lights or high wattage really because its such a small place we are using it in, thoughts on this? What about some kind of Florescent kit that is dimmable, is this possible? We would want the dimmer to not be on the light panel itself but somewhere else like some way to plug it in and dimm it that way from a station likely near the editing bay, we will likely be running capture cards for direct capture to the computer via HDSDI!

Thanks!
 
Hopefully someone else will weigh in with a better answer, but my initial reaction is -- it's not likely going to work out satisfactorily.

When lighting a greenscreen, you want the smoothest, most even, flattest, widest, softest light you can get. That's pretty much the opposite of most LED's. Even a large panel like the 1x1 delivers a comparatively "spotty" light, as opposed to a big ol' softbox or a wide flat fluorescent bank.

Second, dimming LED's can cause absolute havoc with CMOS cameras. You'd have to test your specific lights with your camera to see if they're a problem or not.

Third -- greenscreen needs a lot of space to be done properly. If you have too small a space, you can't get enough separation from the background, and that results in a ton of green spill all over your subject. And the space you're describing is way too small; I like to have an absolute minimum of 10' from the subject to the greenscreen, and that would eat up most of your space.

For tight spaces you may want to consider one of the gray bead backdrops with the ring LED light, like the Chromatte/ReflecMedia system. In general I don't like them as much as conventional greenscreen, but where they shine is in small constrained spaces, so maybe it'd be the best choice for your scenario. You'd need no permanently-installed lights either.
 
I scaled down a few years back and now keep a small green screen setup for knocking out TV spots in the down stairs of my 125 year old carriage house. My screen is 15'x15' and if I were starting from scratch I might light things differently, but in my scenario I re-purposed some twin tube Biax Fluorescent light fixtures I already had, and loaded them with KIno Flo 55w 55C-K5X Green Screen 550 tubes. I use these to light the green screen, with any spill flagged off. This gets very important as Barry has pointed out. I used a handy little iPhone app called Green Screener to quickly get the light spread in the ballpark. Because of my small room size, I generally run some degree of minus green gel on the talent's back lights. Black Harbor Freight moving blankets can be strategically hung at various points from the ceiling to flag off spill, and then quickly rolled up and hook & looped out of the way when not needed.
 
I agree with Barry on that flos are the way to go. I just relit a screen that had been lit with Arri LED fresnels and changed it to flos. The problem wasn't that the Arri's caused issues, they had been installed at a bad angle and we felt that the broader and more even field of the flos were better.

However, I disagree slightly that you need a ton of space between the screen and the subject. In the TV world, the subject (weatherperson) commonly stands only a few feet from the screen. Not only do they only stand a few feet away, they commonly reach back toward the screen to within inches. Obviously this causes shadows on the screen so that doesn't work if you want a realistic key. I have been finding that the keying technology in TV equipment is getting so good that it is able to overcome much more than in the past.
 
Biax flo's are really the bomb for this - especially that they're just so cheap now. I use two duals on the side (sometimes two on each side, one atop the other for a tall source), with diffusion arched across the barn doors. I've never sweated what sort of bulbs were in them, but if I have to tone them down, I have used green gels vs. ND. Test test test.

I made a couple of these with china ball parts and hang them from above when I use my 20' screen. You can put any size spiral in them as needed. Even clip lights are decent, with diffusion.

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I usually do something like a tungsten with 1/2 CTB, or a daylight source for backlight, depending on what the key will look like. I generally don't go overboard with the back light unless I've done a tight storyboard or have a background plate that calls for it. But having a good ten feet between screen and talent is a world of difference in easy keying. And, shooting AVCHD or DSLR, you really need to dial in your screen lighting. RED or something raw & big, not as much worry.

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As I said before I don't have a ton of space so a 4x4 kino bank while a simple solution will not work, I need solutions that are smaller, Michael are the biax flows dimmable or do you have to use filters?
 
If you're short on space, don't try conventional greenscreening. You're gonna hate life. Chromatte is the way to go in a small space.
 
There are plenty of biax models to choose from, some dim, some don't - from the cheap plastic "Flolights" with goosenecks (those are light enough to hang from an office ceiling with a grid clamp) to kinos.

None of my units dim - I just clip ND to 'em, or even wrap 'em in black or white net - they just don't put out much heat. For green screen I'll usually double up the diffusion.

One thing you can do is check what IRE of the screen your keyer likes. Do some tests and make a note. Keylight likes saturation, but not too bright. Can't recall my favorite exposure offhand, I've gotten where I can eyeball it.

But I agree with Barry regarding space - your space is 16' x 17', not a lot of room for lights, camera, and space behind the talent - unless you're just doing headshots...
 
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