Lighting for greenscreen

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Speedvark0

Member
I'm trying to light my DIY greenscreen. I've read quite a bit on the subject, and I'm seeing that you need softlight in order to get your subject looking good, I know to accomplish this you need a softlight box. I found plans for a DIY soft light box, and am considering building it, but couldn't I get a decent enough soft light using work lights and umbrellas?
 
Yes, umbrellas will work. The bigger the better. 18" umbrellas might be a little small. 36" or bigger would be better. Keep any direct spill from hitting the screen. You can also bounce worklights off foamcore and that'll work too.
 
Speedvark -

Green screening is far easier than people realize.

When I was a student at NYU I PA'd for a 6 commercial Cadillac campaign and we completed a tremendous amount of green screen work. Because of this, I was taught by one of the best commercial DP's in the business...and I was stunned to find out how simple this is.

1.) The major issue is radiosity (which could commonly, but inaccurately, be described as reflected color). Your goal is to move your subject far enough away from the green screen so the green screen's reflected light does not interact with the subject. I usually maintain a distance of 20 feet.

2.) The green screen needs to be lit evenly and brightly. Can you remove a green screen with dark spots? Sure, but it's more work! Why force your compositor to work with multiple matte regions or roto-matting, which takes a lot of time? Why not take the extra ten minutes to have an evenly lit green screen? Use kino flos, diffusion or softboxes to create a soft, extremely level amount of light without hotspots. Keep the entire screen within half a stop.

3.) You can light your actors any way you want. I've never heard anyone say you have to soft light actors. How you light your actors is completely irrelevant with one exception...none of your subject's light should spill onto the green screen. You are creating two distinct lighting zones...one is for the green screen and one is for your subjects...and those lighting zones MUST not interact with each other.

4.) It's important to note that you can use ANY hue. Green is the most convenient. However, I prefer to refer to this method as "Pure Hue Replacement" to remind myself that different situations require different colored backgrounds. For example, if you are doing a particle effects shoot (dust, rain, explosions) you should use a black screen because the particulates will have radiosity issues with a colored background and you'll end up losing some of the particulate's volume in compositing. Alien Resurrection attempted to use red screens. The logic was that red light travels the least and therefore they could get the cleanest composites because of reduced radiosity issues...unfortunately, red screens require more light...which heated up the set...which caused the spaceship models to slowly warp during shooting. If you have back issues of Cinefex they talk about the entire "red screen disaster". Blue screens are still used to this day.

Black, red, green or blue it is all the same concept...pure hue replacement. And the greatest factor in achieving a high quality result is controlling radiosity.
 
Chinese lanterns - the poor person's spacelight. Or a bunch of 200w 8U bulbs with no diffusion at all. Many times space lights or fisher lights are used and that's all. So yes, softlight can be a good thing for a number of reasons.

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I saw some shots from the set of '300' and it seemed they had nothing but fisher lights overhead in their green screen stages. Fisher lights are nothing but huge/long tungsten softboxes that take several people to handle when they need to be moved. If there were other lights they were hidden from view.

But when would you mainly use softlight only? As the previous poster said, if you want other lighting you can do it but if you have a green floor too (a total green screen stage on all sides and floor), then that's one reason they mostly only use one type of lighting and that being soft. So everything is nice and flat and even with no hot spots hitting the screen. Softlight from fluorescents and/or diffused tungsten or HMI will go a long way toward reducing the overall shadows on the set and evenly lighting the screen and actors.
 
one of the reasons I like to use softlights is the lack (or softness) of shadows projected onto the greenscreen itself. Especially when I am lighting in a confined space without the luxury of getting good separation from the screen, also when the floor is to be in shot. They just seem to make everyones life easier.
 
P.Pictures, that was a great explaination. I agree, light ng green is much easier than you think. I've done a ton of it this year and I think the single most important thing, after even light, is the distance factor that you wrote about.
I've mostly been doing full figures that walk onto screen, sometimes in pairs. Once was a guy named BEN, who was in a bear costume, but that is another story. I use a 40x40 green-sceen that is placed about 50 feet from my subjects, who are raised off the floor, standing on a stage.
Now I realize that most people will not have the room, money, or time to do it up this big, remember that the further you can get your screen from the subject - the better.
As for lights, sometimes I used two 5K's on either side with a few mighties low and in the middle, but on the last one I just used two studio 2K's and bounced some mighties off white cards, down low, for the middle.
Your zebra meter is a great tool to help you figure out how even the light is and where to raise or lower the light levels. If you are not sure, and have the time, do some tests!
Over all I try to have the green be a stop lower than the subject and I like a bit harder rim-light on them as well. This helps define them and I have read, but not needed to try, that you can put a bit of -green gel on the rims in order to help with the green spill. I would only do that if I had no choice.
Have fun, and good luck!
-Wilson
 
Yes the magenta gel is used for greenscreen rim light and amber for bluescreen. the idea is that those colors are opposite on the color wheel from green and blue and counteract the spill. But today, with the spill reduction algorithms in most keying software its not so necessary any more. Definitely can't hurt though.
 
Thanks

Thanks

Thanks for all the help. Information that is worth more than gold, so what I'm seeing is that soft lighting is for the green/blue/red screen only. makes since. Space lights or fisher lights are pro lights though right, and won't be found at the local hardware giant?
 
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I posted in your other thread too. The one I've used most often is the 8U 200w bulb like this:

http://www.teksupply.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10053&storeId=10001&productId=65629&langId=-1&division=TekSupply&pageId=ItemDetail&parent_category_rn=&top_category=&breadcrumb_trail=Lighting+Fixtures+%26+Bulbs%7CLight+Bulbs&breadcrumb_categoryIds=35044%7C35054&isDoc=

But some use a "CFL tree" made out of Edison Y sockets and 30 to 40w Edison (E26/E27) based CFL bulbs mostly commonly in daylight colors. The CFL tree may be more cost effective and more accessible where you are also.
 
how do you use those bulbs, when the majority of the time, i can only find wires with sockets that take a maximum of 75 watts?
 
Like this:

http://www.coollights.biz/clsft1-cool-lights-fluorescent-video-softbox-fixture-p-33.html

This was the simple fixture I developed to use with them for just that reason--there aren't such fixtures available for the most part and certainly nothing I would list as low cost.

If you want to DIY something you need a mogul E39 base and wire it up securely like in the recent Chinese lantern thread were Ian from Australia was explaining his setup.
 
but that is an entire package, how do you fit that in a china? or would i have to purchase the entire fixture and remove the wiring?
 
No, on that page the only thing I'm selling is the fixture itself. No softbox or bulb. You have to get the bulb separately because I didn't find the good source of them yet where I could offer it at a good price but I'm still working on that. Anyway, the softbox fixture can be used either in a chinese lantern hanging upside down or in a softbox. If you use it in the chinese lantern it just takes a little adaptation to the inner skeleton of the lantern to attach to the softbox fixture. I don't have the pictures with me right now of the chinese lantern on the softbox fixture but its a good combo...
 
I've used 300 watt bulbs quite often in china balls. If you find an electrical supply store you can find these, and even in some big box stores.
An old trick is to wire two ceramic fixtures inside the same ball, both with their own cords, labeled so that you can put a 100watt and a 300 watt bulb in there, or even a daylight and a tungsten bulb.
You can use bailing wire to make a HARP. A HARP is simply the wire harness that comes with the balls, with a long piece of 1/4 threaded tubing (like the stuff you buy when installing a fixture in your house only longer) attached to your ceramic fixtures with a threaded adapter. The reason for the tubing is that it allows for something to connect the wire harness to AND it keeps the bulbs in one place as to not touch the side of your paper china ball and burn up your shoot, really ruining your day.

Good Luck - Wilson
 
Speedvark0 said:
I'm trying to light my DIY greenscreen. I've read quite a bit on the subject, and I'm seeing that you need softlight in order to get your subject looking good, I know to accomplish this you need a softlight box. I found plans for a DIY soft light box, and am considering building it, but couldn't I get a decent enough soft light using work lights and umbrellas?
Click to expand...

How big of a set are you looking at ?

BTW, here is a link to an article at lowel edu for lighting smaller sets. http://lowel.com/edu/lesson_green_screen.html I've also had good luck with Reflecmedia
Here's one more Lowel set-up with Fluo-tec lights. http://lowel.com/fluotec/setups/chromaset.html
 
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