Since I own both a DVX100 and an HVX200 camera which I often use for greenscreen shoots, I'm sometimes asked by filmmakers who are new to compositing what my advice for shooting greenscreen with these cameras is. Much of my advice to them is independent of camera, although I have specific tips and tricks for the DVX100 and HVX200 that I bring up, so folks who don't own them will still get some ideas about greenscreen shooting that may be helpful. (Please be aware that this article originated as a series of emails based on filmmaker questions that I put together to answer some of the common questions about greenscreening. As such, if it feels a little more chaotic and free flowing than my other articles, that's why.)
First off, my best advice on compositing is: "As much as possible try to rely on the tools and what they are telling you and not on yourself."
There are too many accommodations that our visual systems can make. And in the end, it's what the camera sees and the compositing software sees that matters most.
And what the camera and software see is what they see, no matter what I think about it or how I think it is supposed to work.
To get the best possible keys, you must match up the color that is recorded in the camera, and then verify the settings with the color.
Let me explain by showing what I did when I first got started with greenscreen work..
First, I printed a matrix of colors using Photoshop and a color printer. I hung this matrix on the wall, lit it, and shot a few seconds with every combination of color matrix setting and gamma setting on the camera. I then took stills from each setting into photoshop and compared them. What I was looking for was the color that had the most separation between green, red, and blue – the best difference the camera could see. So I used the eye dropper tool to sample each color and examine its RGB values.
Surprisingly, some colors that I thought were very similar were not. For example, one had only 5% more green than red or blue. And it didn't look any duller than something with 35% more green – which was going to make a better composite. Also, surprisingly, most colors had a lot of gray in them. Like 35% red, 35% blue, and 38% green. Almost pure gray. I chose the best color I could find, took it to the paint store and found a close match--Botanical Green, I believe--and then painted a wall in my studio.
I actually had a number of paint chip samples from the store and when I compared the off the shelf color with the color I had selected, I couldn’t see the difference. So I tested in camera, took a still, and sure enough, in the Photoshop dropper tool it was very, very close. I don’t know how much I saved picking that color over mixing a unique color. Probably saved a buck. I know I saved a ton over photogreen paint. [Editor's Note: To see a tutorial on using this paint to create a movable greenscreen, check out our tutorial: Build Your Own Greenscreen.]
Then I went back and ran the color/gamma tests again to verify the best settings with that color.
