Good lighting is directly related to how strategically you position your photography subject. You want to get the model as far away from the chromakey screen as possible. This reduces the possibility that light will reflect off the background and spill onto the subject.
You have good flexibility if the subject is 6 to 10 feet away from the chromakey screen. Light from the background falls off after 5 to 6 feet, so you end up with less color spill. This distance also makes the foreground a bit darker than the subject, which is helpful.
You want the background to be about a ½ to full stop below the foreground. If you are only using two umbrellas, 6 feet or more is ideal. If your subject is 6 feet or more away from the chromakeey background, the background should be naturally darker due to light falloff.
A distance of 6 to 10 feet is ideal but 4 feet is the minimum. It is possible to have a successful photo shoot with the subject closer than 4 ft, but other problems get introduced, like shadows on the background or bright color spill. At under 4 feet, you are potentially setting yourself up for a lot of Photoshop work.
We have seen situations where the subject was a couple feet away and it worked fine. In that case, the lights were above the subject and pointing down, which prevented any shadows to appear in the head/shoulder shot. This setup would probably not work with ¾ or full length poses.
Step Seven : Choose new chromakey background