- HOW TO BOOST GREEN SCREEN AFTER EFFECTS KEYLIGHT 1.2 SOFTWARE
- HOW TO BOOST GREEN SCREEN AFTER EFFECTS KEYLIGHT 1.2 PROFESSIONAL
Of course it's important to light your screen extremely evenly. That's why Composite Components also sells Digital Green (and Blue, and Red) fluorescent bulbs to illuminate their screens with. The reason why it doesn't photograph as absolutely pure green is that there is simply no material, dye or pigment that absorbs 100% of the red and blue in white light, while reflecting only green light. In order to be any better, it would have to BE electric!
You should see it in real life - it looks electric. So believe me when I tell you: this is quite literally the best greenscreen material you can buy. Their stuff is the gold standard in Hollywood, and they were rewarded with an Oscar for their screens in 1996. Jon Erland, the co-founder of CC, has written 15 papers for the SMPTE journal on the subject of traveling mattes. The greenscreen you see in the test shots I took is called Digital Green, and it comes from a great company called Composite Components. So you may want to keep that in mind when reading my posts about greenscreen.
HOW TO BOOST GREEN SCREEN AFTER EFFECTS KEYLIGHT 1.2 SOFTWARE
I write keying software for a living, and have been writing keyers for over 10 years now. Notice how dark the Red and Blue patches are on the Macbeth in the 738 image! Crazy. I've attached three images - one "clean" with no gel, one with Lee 738, and one with Lee 138. Other contenders are Rosco 3304 & 88, and Lee 88. In particular, Rosco 388 ("Gaslight Green") looks good. I'm going to test more of these subtle gels in the near future. Then again, if you have even half a stop to spare, the 738 blows it away. Definitely a step up compared to not gelling the lights. Not too shabby, considering you don't have to compensate the exposure at all. (Although you should always flag off your GS lights so they don't interact with the subject. And if you're in close quarters and can't avoid having your greenscreen lights hit the subject, it wouldn't be a total disaster, because it isn't so insanely green. It's nice because you don't have to compensate exposure at all. I also tested a more subtle green gel, Lee 138 ("Pale Green"). You would have to play a lot of games with your white balance to get it to photograph as pure green. BTW, avoid Rosco's "Chroma Green." It's too blue, and too dark. Still a great reading, but if you can get your hands on the 738, it has the edge. Which gives an 86% difference between G and R&B. If you only have access to Rosco, #86 ("Pea Green") is the closest to Lee 738, but not quite as nice. I instantly ordered a bunch of T12 sleeves of 738 for my cheap fluorescents when I saw this. (!!!) The difference jumps from 58.5% to 92%! Our matte can now utilize 92% of the values between 0-255. Compensating by opening up the aperture, our reading is: With the 738 on, we lose roughly 1/2 stop of light. You literally can't buy a better greenscreen material than the CC Digital Green. This is the best we can do without help from the lighting. This means our core color difference matte will only have 58.5% of the values between 0-255 to work with. The difference between our G channel and the R&B channel is 58.5%. R:31% G:92% B:36% (sampling the screen to the left of the "brown patch" on Macbeth) Without the gel, the greenscreen is reading at:
HOW TO BOOST GREEN SCREEN AFTER EFFECTS KEYLIGHT 1.2 PROFESSIONAL
I tested by gelling a flash unit and photographing a professional greenscreen from Composite Components.
So for a relatively small decrease in exposure, you can almost eliminate the red and blue light which is corrupting your greenscreen.
Since filters are subtractive, a good green filter will hold back most of the red and blue light, but allow most (but not all) of the green light to pass through. The theory is, if you throw green light at the greenscreen, it has no choice but to reflect a greener green for the camera.
In the quest to get a more pure green greenscreen, I've been testing lighting gels from Rosco and Lee.
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