Chroma key technology allows filmmakers to film objects or actors against a a colored screen and then replace that background with just about anything the filmmaker can imagine. Many of the elaborate scenes in the Star Wars prequels and Lord of the Rings utilized chroma key technology to create worlds and backgrounds that simply could not exist in real life. Using this technology yourself can be done fairly easily provided you follow some basic tips.
Create Proper Spacing
Space the person or object being filmed around 8 feet in front of the green screen. It is important to get the proper spacing so that the objects or characters don't cast a strong shadow on the green screen.
According to DigitalProducer.com you should also place the camera as far away from the subject as you can. The reasoning is that a green screen can have imperfections or subtle wrinkles and folds. This will distort your image when you do a chroma key replacement and make the background look obviously fake. This is especially true if you have created your own green or blue screen out of cloth.
Avoiding Simple Mistakes
Make sure that the objects you are filming in front of the green or blue screen are not colors that are close to the color of the screen. To be safe, run a test shot and make sure that the colors of all the clothing and objects don't blend in with the background.
Keep in mind that metallic surfaces that are shiny can also cause headaches with chroma key replacement, because shiny metal reflects the colors around it. Because of this, portions of your metal object will be reflecting the green or blue screen, making the image unusable later. This can even happen with oily or shiny skin if you are not careful. Make sure that nothing is catching the light of the screen.
Lighting the Set
Make sure that you pay close attention to lighting. You will need to create an even lighting scheme for the set when you are working with chroma key replacement and green or blue screens. Don't use too much light, as this can cause the color of the screen to bounce off the screen and onto objects or people. Make sure you also pay attention to backlighting your objects and actors or you will have uneven shadows on the screen, which will result in headaches later.
Tags: green blue, sure that, blue screen, chroma replacement, green blue screen, green screen, color screen