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Old November 17th, 2008, 02:40 PM   #1
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Projecting a green screen onto a wall

Hmmm . . . not sure about this.

I am shooting a corporate for a client and have travelled to the US to do so. That means I have limited access to equipment. The locations that were described to me over the phone aren't really as I was expecting them to be and won't meet my needs. However, the client has a large conference room with a big screen and data projector. The room can be completely blacked out. What I am wondering is whether it's possible to project a green image onto the screen and use that as a green screen background. The talent will be able to stand away from the ceiling mounted projector so as not to cause shadows and I have 2 x 600W lights and a pair of Lowell Pro 250W focusable lights (and lots of space) to more than adequately light them.

What is it that I am missing here? There must be something that will mean this won't work!

Can anyone make me see sense before I commit to using their conference room? Or better still, tell me that it's a great idea!

Thanks,

Ian . . .
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Old November 17th, 2008, 03:21 PM   #2
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Interesting idea. Having never tried it, I would only caution that your white balance be correct so that the screen 'reads' green, and the lighting (for the talent) doesn't spill on the screen. The talent's lighting should be of similar color temp to the projector, otherwise you might have color-balance issues.

If you have access to DV Rack on a laptop or some portable vectorscope, you can easily check out the color balance (handheld meter would also be great to have).

Best of luck.
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Old November 17th, 2008, 03:52 PM   #3
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Oren, many thanks. Hadn't considered the colour temp issue. Luckily I do use DV-Rack so I'll look at that tomorrow. Thanks again. Ian . . .
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Old November 17th, 2008, 11:14 PM   #4
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I think the actual color of the screen isn't particularly important- as long as it isn't too close to the color of something the talent is wearing, their eye color, hair color, threads in the suit jacket or tie color, etc. I've heard of people pulling successful keys with red in addition to the standard green, blue, or whatever.

Evenness of the screen though is important

Maybe a nice Windows "blue screen of death" would suffice.
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Old November 18th, 2008, 02:58 AM   #5
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Maybe you can rent or borrow a green screen. Let folks here know where you are and, if you're lucky, there will be someone nearby who can get you a good bundle of fabric that you can use for a few days.

Or maybe buy an EEFX.com green screen. It folds up nicely, unwrinkles on its own, lights extremely evenly and gets excellent results.
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Old November 18th, 2008, 08:27 AM   #6
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Jim, BSOD would work!

Dean, good idea. I've already been in touch with the local videographers association who have already been very helpful. To be honest, I'm working to a tight budget and I'm reluctant to spend any more - especially as the pound is weakening against the dollar by the hour! Additionally, I have full greenscreen capability at home so I'd be doubling up on things I already have (but can't easily throw on a plane).

I think I'm going to have a go with the projector (we have now found a room with back projection which should be better still).

Thanks for the suggestions everyone. I'll let you know how successful (or otherwise!) we are.

Ian . . .
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Old November 18th, 2008, 08:38 AM   #7
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The biggest problemis spill, espcially since a projection screen is deisgned to reflect as much light as possible. Also, viewing angle of the screen is more limited than if you were using a green cloth backdrop.

Finally. lighting your talent without light spilling onto the screen is also a challenge. I've thought of using my 72-inch projection TV as a green screen, but haven't tried it yet. It's picture is also directional.
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Old November 18th, 2008, 09:10 AM   #8
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Good points, Paul, thanks for bringing them up.

We are fortunate in this situation in that a) i am only shooting head and shoulders, b) I can position the talent a good six feet in front of the screen which will help with spill, c) the room is very big so I can be very flexible in where I place my lights and d) I'm shooting head on so no worries about angles.

I'll keep an eye on light reflecting off the screen.

Thanks again.

Ian . . .
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Old November 18th, 2008, 09:21 AM   #9
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What about buying a roll of paper? I realize you said you don't want to spend anymore. Understandable. But, you can get a roll of green paper for around $40.00. Not much, if it saves your shot and makes your life easier.
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Old November 18th, 2008, 09:48 AM   #10
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Also good advice, Josh, thanks. If it goes horribly wrong I'll probably do just that. We're just setting up to make some tests at the moment so let's see how it goes.
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Old November 18th, 2008, 09:54 AM   #11
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I may be way off here but projectors always seem "flickery" to me. I really don't know much about projectors but do they work somewhat with a framerate? Meaning, would the projector project out the green color image 24 times a second? That may affect you if you shoot at different frame rates and the greenscreen flickers or is in and out on frames. Kinda like shooting a TV or computer screen. Seems like an old slide projector with a green slide would be more constant than a digital projector.
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