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Lighting a largish green screen on a budget (dollars and amps)


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#1 Mathew Rudenberg

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Posted 11 June 2008 - 02:44 AM

If you're not all sick of greenscreen posts I would love to have some help with this setup from some experienced lighters and shooters...

The problem is I need some help determining the number and size of units for the screen, as well as the distance I should rig them from the screen to have it evenly illuminated.

The green screen is 38' foot long, with a curve and another 19' wall at 90 degrees. It is 18' to the speedrail grid.

The problem is I have only 150A to light both it and the action below... and we can't afford a genny.

We're shooting on the Red for color space, prob in 2k because i believe dof will probably do more harm than good for compositing. So I'd prefer to light to about a 2.4 at 320 iso.

I'm thinking kinos to keep the amperage costs down, and although I've read mister David Mullen's excellent posts on green screen and how green tubes are more efficient, the fx guy would prefer not to use green tubes.

Would six 4x4 kinoflos be enough to light this evenly from the ceiling?

if not how many would I need before having to beef up to image 80s?

Also how far do I hang them to get even lighting?

Thank you for your time and experience
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#2 David Rakoczy

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Posted 12 June 2008 - 11:33 AM

Brother, you are going to need a lot more 'Light'... and Amps.

The first thing is, do you need to Light ALL 57ft of Cyc? Will you be seeing the Floor? How much more sq. footage does that total? I would be looking at a Genny w/ Space Lights. Remember, you are going to be Lighting your Subjects as well. They will most probably need to be even Brighter and the Lamp will probably need to be well out of Frame which could be quite a distance on that size Cyc... sooooo.... looking at 10ks/ 5ks or even little 2ks you will eat up that Amperage in a couple flicks of the switch.

Sounds like they need more $ or simplify.. scale smaller... etc. Remember, only your Subject needs to have Green behind them. The rest can be junk matted for Wider applications.

Best of Luck!
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#3 Mathew Rudenberg

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Posted 12 June 2008 - 04:16 PM

Brother, you are going to need a lot more 'Light'... and Amps.

The first thing is, do you need to Light ALL 57ft of Cyc? Will you be seeing the Floor? How much more sq. footage does that total? I would be looking at a Genny w/ Space Lights. Remember, you are going to be Lighting your Subjects as well. They will most probably need to be even Brighter and the Lamp will probably need to be well out of Frame which could be quite a distance on that size Cyc... sooooo.... looking at 10ks/ 5ks or even little 2ks you will eat up that Amperage in a couple flicks of the switch.

Sounds like they need more $ or simplify.. scale smaller... etc. Remember, only your Subject needs to have Green behind them. The rest can be junk matted for Wider applications.

Best of Luck!


Thanks for the response,

I appreciate your advice, I'm planning to go daylight in general and HMI on the foreground to deal with the red native 5000K issue (it gets noisy at tungsten temps), and also to give me some more bang for my amps. I agree it's on the edge of being possible either way, and I feel like I'm not going to know if it'll work for sure till I get in there.

Still, I'm less worried about the foreground as I've lit that kind of stuff with less before, even on a camera as slow as the red. Also I can dance the lights around shot to shot, and I don't think I'll ever see all of the cyc at one time, although I'd like to light as much of it as possible so as to not have to adjust lights up there...

My main concern is getting the green up to about 40 ire, especially considering all greenscreen I've shot so far has been lit from the floor (12 by with a kino on each side usually).

Right now I'm planning to line up 8 daylight 4x4s 3 feet between each and 9 feet away from the screen and 18 feet up.

By Pythagoras this gives me 20 feet to the base of the screen, and my box book tells me that that a single 4x4 gives me 8fc at 20 feet, which is f1.4 at 320 ASA.

That is not enough, however I'm hoping the kinos on either side will spill enough (5fc each at 25') to boost that to at least a 2.0, pref a 2.4.

Of course, doing some silly math doesn't compare to real experience rigging toplit greenscreen, which is why I'd love to get some feedback.

I could compress them and use less of the screen of course, which I am happy to do if necessary. As for the floor, I'll only need it for a couple of specialty shots and I can bring in some units closer for that.
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