Green screen shooting is for more than gimmicks like putting someone on the moon or a roller-coaster. Being able to isolate your subject from its background provides limitless creative opportunities.
Here is the equipment you will need:
- One Chroma Key green surface: This can be a muslin drop cloth, nylon cloth, paper, or even a painted wall.
- One HD camera (720p or 1080i) with tripod
- At least five quality lights: 600W Tungsten or equivalent (brighter is even better). You can get by with three lights, but you will not get the best results.
- A large area to shoot in with at least 10′-12′ of height (if shooting full length subject) and at least 30′ of length
- Miscellaneous Gels, scrims, or cookies as needed for look you want on subject
Here is how to set up the shot:
Before discussing the lighting (which is by far the most important part of the setup) let’s talk about positioning. Place the green screen at the far end of your space at least 25 feet from the camera. Your subject should be positioned 7 to 9 feet from the screen. You may need to make adjustments to the screen to make sure everything remains in frame.
Lighting is the most important aspect of getting a great key, i.e., removing the green background in editing. The goal when setting up the lights is to minimize the appearance of shadows. This is important because it is very difficult to key out a shadow and much easier to put one back in. Save yourself time and anguish and light it right the first time.
Lighting the Screen
You need a minimum of two lights for the green screen. These lights should be soft and even over the breadth of the screen. You may need to swivel them left or right to make the screen as evenly lit as possible. Try to avoid hot spots or cool spots especially in the area behind your subject. You may need more lights for even coverage on a larger screen.
If you plan on tracking a moving subject with the camera, a tracking point can really help you with your composite. They will help you to see where in space your subject is and where objects should be placed. These points can be little round colored stickers or bits of tape.
Lighting the subject
Your subject should be placed on a plane that is just in front of the lights which are lighting the green screen. This is about 7′-9′ away from the screen and at least 15′ from the camera lens. No light from the two fills you aimed at the screen should spill onto the subject. Direct two fill lights onto your subject; it may help to turn off the fills on the screen so you can get an idea of how the subject will look after the background is keyed out. Make sure there is enough contrast between the subject and background; a good guideline is for the background to be one stop down in comparison to the subject.
An additional ‘hair light’ will bring your subject off the background and will make your key easier to do. Place this light behind and high above your subject. Make sure it is not to bright, adding an unwanted shadow.
As a final check, make sure there are no shadows or ‘hot spots’, areas where there is uneven intensity in the lighting.
The example below shows the effect of poor lighting on the final composite:
The original on the left has several issues. First the subject needs more light to help contrast her from the background. Also the fill-lights on the green screen are uneven. This makes it more difficult for the software to key out all of the green. There are some very powerful software options that can compensate for bad lighting, but your results will always be best if you start with a good setup.
In this second example, you can see that the subject is lit properly. The fill-lights on the green screen are even, without any ‘hot-spots’. The subject is evenly lit and contrasts sufficiently with the background.