Chromakey Green: Three Painful But Easy to Avoid Mistakes

Chromakey green is used all over in Hollywood studios because it can make the impossible possible. Amateur filmmakers use it in their films because it brings the cost of creating their films down considerably and they can make their movies much faster. Whatever the reason, it’s clear that chromakeying is here to stay.

The beauty of using chromakey green is in the simplicity: all you have to do is set up a screen, set up the lights so the lighting matches your end scene that you have in mind, film the action, and then apply the green screen replacement effect using software. Once you know what you’re doing, you can blast through this process and create stunning-looking scenes with little time and effort.

But while this process becomes easy with practice, it can be much harder–almost to the point of being a nightmare– when you don’t know what you’re doing when you’re starting and you and make a few common rookie mistakes when using the green screen. To help you sidestep these potential problems, we’re going to cover a few common mistakes people make when using a green screen so it’s smooth sailing for you when you give it a go. Note that pretty much all of these problems have to do with the lighting of the green screen. If your screen is dimly lit or if you have shadows on it, you’re going to have a hard time when editing to create the effect you want. The goal when lighting a green screen is to have it be evenly colored. The better you achieve this, the easier your editing job will be. To keep the green screen background evenly colored, keep these three factors in mind:

1. Make sure you have enough light on the screen that it looks evenly lit. A barebones setup uses three lights: two lights set up as “fill” lights, to cancel out the shadows created by your subjects, and the third set up for lighting your subjects. But the more lights you have, the better, since you’ll be able to light the chromakey green screen more evenly.
2. Make sure your subjects are acting far away from the green screen, NOT close to it: keep your subjects at least five steps away from the green screen while the camera is rolling. If your subjects are closer, they will likely cast shadows onto the screen and those will make the editing process a bitch, so keep your actors away from the screen. This is probably the most common mistake made with lighting the screen because it’s easy to forget about when you’re in the middle of the chaos of filming, but it is very important.
3. Make sure you use a matte surface for the chromakey green screen, not a shiny one. Whatever material you use for the screen, whether it’s a paper screen or a painted wall, or a linen sheet, or a muslin canvas, it’s important that it isn’t shiny, because the shine and glare that will appear in your shots from the lights bouncing off these materials will, again, create uneven coloring of the screen and make your life hell when it comes time to edit the footage and apply the keying effect. A matte surface, in contrast, will diffuse the light and result in much more even lighting of the screen, which is exactly what you want. So make sure your chromakey green screen has a matte surface, not a shiny one.

If you keep those three things in mind when setting up your green screen, you’ll make things much easier for yourself in the editing room and shave a lot of time off the process.

Alright filmmakers, talk soon.

David Carthage

David Carthage is a writer and entrepreneur with a passion for filming and an acute attention to detail. Click to visit his site for helpful tips on using chromakey green, and learn more about using green screen backgrounds here:

http://chromakeygreen.org/chromakey-green/chromakey-green-what-it-is-how-its-used-and-why-3