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Craigers
04-04-2006, 01:41 AM
Hey Y'all
Anyone know the optimum ratio to light a green screen vs. Key light on subject when using VT 4 as the Keyer? I'm used to lighting the green screen about one stop below the key when I'm shooting for AE and others but haven't shot using VT 4 as keyer before. Any advise?

Craig Finetti

billmi
04-04-2006, 07:34 AM
If you normally shoot DV, you'll find better quality hooking your camera to the VT, and recording as an RTV. DV compression throws away enough chroma data that it makes it more difficult to get as clean of a key.

Other than that, in my experience it's not so much an issue of a ratio of the subject's brightness to that of the key, as it is making sure the background material is even (i.e. if it's fabric, no wrinkles that will cause shadows) and evenly lit. Also, that it is distinct in color from the subject (i.e. minimal green tones in your subject if you are green screening.)

joseburgos
04-04-2006, 09:10 AM
If you have to use DV footage, then I suggest Serious Magic's Ultra.
It is just awsome for doing greenscreen but do not render out of ultra in anything other than uncompressed or you will not get the alpha.
I think this changed in Ultra2 but can not confirm.

Take care,

ted
04-04-2006, 09:16 AM
And don't forget a good backlight which will help separate the subject from the background. Maybe add a warm gel to the backlight also.
Oh yeh, keep the subject away from the green/blue screen.

Dan Hong
04-04-2006, 10:38 AM
We've been happy by lighting the green to 50% on the waveform. Keep the talent as far in front of the screen as possible, backlight with magenta gel, and record as rtv. I always record directly into the VT and check the project periodically by doing a quick key in the switcher. Even if you're going to do the final key in AE or something else, the RTV is the bomb. 95% of the time I end up just doing the key in VTEdit. We've done some ridiculous keys on some really bad backdrops and had great success.