More and more photographers are shooting digital for compositing using Green Screen or Blue Screen Backgrounds.  This is called chroma keying and started in video production and has now been incorporated into digital photography.

 

Putting together a good chroma key shoot is not difficult, just follow a few basic steps and you're in business.

 

The first thing you need for chroma key is a Green or Blue Background.  Green is the most popular today because it doesn't clash with skin tones and green is easier for your eyes to focus on in your camera.  Both green and blue screens will key well.

 

 

When lighting your green screen you must make sure that all of the area around you subject are evenly lit, by that I mean if you have a 10' wide green screen background and you're only doing some close up work you don't have to have the entire background evenly lit, if you have the lights to light the entire background evenly, then by all means do so.  Usually two lights are used, one on either side of the background.  You don't have to wash the background out with light, you're just trying to accentuate the hue of the background. Your chroma key background lighting set-up should be independent of the subject lighting set-up.

 

Make sure that your green screen background is as free of wrinkles and seams as possible, is does not need to be pressed to have no wrinkeles at all, just the least amount you can get.  Deep wrinkles will hamper your evenly lighting your background.  You can use your light meter to check your background for even lighting.

 

Once you have your background all setup and ready to go, it's time to light your subject.  You should light your subject as you would normally do when not shooting chroma key with the exception of keeping the background scene in mind that the subject will be placed in.  Is it an outdoor scene with directional lighting, or dark indoor scene.  Try to match your subject lighting set-up and poses with their new scenes.

 

In order to reduce spill, light from the green screen background reflecting back onto your subject, you'll need between 6' to 15' of space between subject and your evenly lit background.  Spill light can cause problems with keying your subject,  if you can't get far enough away, you can minimize spill using colored gels on some of your subject lighting, magenta for green screen and yellow for blue screen backgrunds.

 

 

Great question.  There are several approaches to digital photography chroma keying and you'll have do decide which suits you best for your time and skill level. You can purchase ChromaKey software that does an excellent job quickly, or you can use image editing software and do it yourself or with some type of semi-automatic keying action or plug-in for your software.  Either way it will take some time and practice to get it right.  So, take your time and develop your workflow, the results will be astounding.