Making That Green Screen Work For You!

Posted by Ramzi Abed - in Uncategorized - Comments Off

A View From Behind the Meter

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A friend of mine, at Woodbury University in Burbank, presented me with a problem to solve. He had been tasked to set up and shoot a PSA for children in order to encourage them to eat vegetables. There was very little money and he was going to shoot in the sound stage at Woodbury for which he was stage manager but the big element was that Sesame Street puppeteers were going to donate their time for the project. He asked me if I could work with him on the project and wondered whether I had any ideas of how it could be accomplished.

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First of all this was an obvious green screen application with the puppeteers needing to work against an observable image of the backgrounds for the story. These backgrounds would be shot in advance and projected on a monitor in front of them. A secondary consideration was that the executives had to sign off on the finished product on the day of the shoot. So the problem was without much money working in a University sound stage using only the equipment available plus what I could bring to the table how do we make this happen?

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Initially I went by the sound stage to seewhat the university had available. The stage is a working teaching facility and one of the first all LED sound stages in the educational community. It is not large but very workable and has Litepanels Sola 4’s and 1’ x 1’s rigged into the grid running completely on DMX cat cables controlled by a consul dimmer. There were also 4’ x 4 bank Filmgear LED Flos, Filmgear Power LED 160’s, and several Panasonic Af-100 cameras. This was a good beginning and I added a 12’ x 12’ digital green screen with frame, a Power LED 240,  two high rollers, and finally some 2’x 4 bank LED Flo’s. Lastly I brought in two 42” monitors, an AJA Key Pro Mini playback device, and a Panasonic Compact Live Switcher, the AW-HS50N, with the requisite cables for linking all systems. The switcher was the key element in that it has a capability to key out the green and replace it with a background plate entering through one of four SDI inputs. The object of course was to have both the executives and the puppeteers view the composite live on the two monitors as the show was shot allowing the Sesame people to view their work and the executives to okay each segment.

The date was scheduled for a weekend to allow everyone to arrive, shoot, and get back home with the least inconvenience to all concerned. Now this all happened on the Cinegear weekend and I was scheduled to be in Birns & Sawyers booth both Friday and Saturday so I had to do everything by Thursday evening and let my friend fly on his own for the weekend shoot. As it turned out this is exactly how it came down. On Wednesday morning I brought in the green screen and the rest of the set-up parts. I set up the green screen and lit it with two 4’x4 bank LED Flo’s and two 2’ x 4 bank LED Flo’s both daylight and placed it a good fifteen feet from the puppet performance area to give me good separation. I did this to mitigate the back green spill from the lit screen. Next I set up the playing area. A 12’ duveyteen black was hung from a 16’ speed rail at about head height so the puppeteers could work from below and a monitor was set up on a table behind the black so they could view live their movements and read the script at the same time. The performance area was lit by the two power LED’s. The Power 160 through a silk as fill and the Power 240 clean as the key. I used two Sola 4’s as backlights with half magenta to aid in reducing green back spill. Using a few flags to eliminate unwanted ambient spill from the key and fill the lighting set-up was basically in place. The lighting and grip set-up day Wednesday was complete.

On Thursday I returned and placed the recorded background plates in the AJA key pro and plugged it into the # 1 SDI input port on the Panasonic switcher. I then connected the AF-100 into the # 4 SDI input port. Lastly I wired both monitors to the switcher output ports and programmed all ports to allow keying and compositing to take place live. The camera, switcher and the AJA have to be formatted the same for this to really work. Also the recording of the background plates has to be matched to that same format or nothing happens the way you’d like. We switched everything on and held our breath as the Chroma-key switcher took a sample of the green screen color on an evenly lit solid green frame. We then placed an object in the frame and keyed out the background green and to our delight there was the object on the live background plate being played back on the AJA. It was a beautiful thing. My job was finished.

I went to work at the Cinegear Expo and on Monday picked up all the equipment returning it all to Birns & Sawyer. My friend sent me the attached photos. Success is sweet.

-Michael Rogers, Lighting Consultant and Educational Outreach

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