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Old September 2nd, 2010, 12:07 AM   #1
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? about green screen lighting

When shooting green screen, how bright should the back light be in comparison to the key light and the fill light? My goal is to create separtion between the background and the talent. Space will only allow the talent to be about 5 to 6 feet in front of the green screen.
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Old September 2nd, 2010, 01:07 AM   #2
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Don't overlight the screen, otherwise it can cast spill onto the talent edges and ruin the key. Sometimes, using different color temperature bulbs on the screen vs. the talent can make it easier to pull a key. The most important issue is NOT to cast shadows onto the chroma screen. Using soft talent lights and lighting more from the side than traditional 3-point angles can help.

Obviously, make sure there's no green color tints in the talent's wardrobe. I've been on too many shoots where this was NOT obvious to the talent.

Hope this helps.
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Old September 2nd, 2010, 05:14 AM   #3
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hi kevin,
i usually light my greenscreen with 2 x 4bank cool lights with daylight tubes with a sheet of 1/2 plus green gel......... lee 245
the key and fill vary but are daylight balanced
the back light is a 150 dedo 3200 balance which goes warm and gives a nice hilight. the dedo is dimable so i adjust it to suit via the monitor until it plays.
cheers
ian
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Old September 3rd, 2010, 05:47 AM   #4
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Think of the green screen as part of the system that will generate the key.

The screen should be exposed at 50 IRE throughout. The green should be "green". In other words, white balance the camera for the light illuminating the screen. People will argue with this, but in my experience, I can pull a near-perfect key that holds stray hairs and translucent veils.

Your green screen will provide the image data necessary for your green screen software to pull a good key. Compromise the shot and you'll make it that much harder in post.

At this point, the talent will end up being almost a silhouette on-camera. This is when you start lighting for the talent. You don't need a hair light unless the background plate determines the need for one.

If you're looking for realism, then your light has to match the background plate. Direction, quality and quantity is based on the light that illuminated your background plate.

This can be time consuming, of course. But that doesn't mean it can't be fun! :-)
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Old September 3rd, 2010, 09:23 AM   #5
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Dean, always enjoy reading your posts even though I suck at fishing. :)

Question: I can see the advantage of getting your WB from the greenscreen lighting, but won't that throw off the color balance of the subject, assuming it's lit differently?

Also, what's the harm in lighting your greenscreen to only 30-40 IRE as it would reduce spill?

Thanks
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Old September 3rd, 2010, 11:20 AM   #6
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Paul... I suck at fishing, too! Luckily I only have to observe and film others doing it.

The green should be exposed at the middle of the camera's response curve to provide the cleanest green channel possible. Makes it easier for the software to exclude it in the composite.

If you over expose or under expose the green starts to be compromised. While the software can still do it, the task gets more difficult. You want the best possible starting point when doing this sort of thing.

And you will want the same type of light illuminating your subject as the green screen to avoid potential lighting conflicts, especially if there's little room to work.

You should always experiment, of course. Casting a shadow onto green screen, for example, can be very useful in full-length work as the shadow can be incorporated into the final composite.
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Old September 3rd, 2010, 10:40 PM   #7
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Quote:
Originally Posted by Paul Cascio View Post
Question: I can see the advantage of getting your WB from the greenscreen lighting, but won't that throw off the color balance of the subject, assuming it's lit differently?
Once you pull your key you can throw a color correction filter under the key and just correct the subject. I do this all the time.
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