Green Screen Photography
Green screen photography (which can actually be blue as well) is very useful for isolating a subject, usually a person, with the intention of replacing the background later. Green and blue are the most common colors used since these are the most likely colors to not be on your body. However, any color can be used. If the subject is wearing all blue and the screen is blue, this technique won’t work. However, when the colors of the subject are different from the background, the subject can be easily masked off in Photoshop and placed onto a different background.
Steps should be taken to provide even illumination and the most minimal shadows possible. This can be accomplished by using multiple light sources to fill in the shadows that would be created by a single light source. Here is a good photo which shows how to accomplish this effectively:
Camera Settings for Green Screen Photography
1. Your white balance should be set to Flash or Manual White Balance. Use a gray card.
2. It is best to always use ISO 100 or even lower if your particular camera can go lower. Lower ISO numbers provide less noise and make extraction easier and cleaner.
3. A wide aperture = lower number will also provide less digital noise in the final image. A wider aperture will also reduce the depth of field, which will cause the background (green screen) to be a bit out of focus. This can help provide a more uniform background of a solid green color, which makes extraction of the subject easier. F8 or less is recommended.
4. Shutter speed isn’t particularly important since a flash is being used.
Other Tips for Green Screen Photography
1. The subject should be at least 6 feet in front of the green screen. This is because the green color will actually reflect back onto the subject.
2. Make sure there are no visible wrinkles in the screen if at all possible. If you are using a fabric screen, you can actually iron out the wrinkles. This is tedious but worth it since the wrinkles create shadows, and therefore an uneven background which makes extraction of the subject more difficult. If using a paper background, obviously ironing isn’t an option. In this situation, just do the best you can to stretch the paper taut to minimize the wrinkles. If there are any wrinkles that can’t be ironed or stretched out. The multiple light sources will help to fill in the shadows which result.
3. Finally, it is recommended to shoot in RAW mode. This way there is no JPEG compression and there is more leeway in the final edit.