You can dramatically reduce the green spill and color cast in your images by simply optimizing the green screen and green floor size. Most people use too large of a green screen and green floor. This causes a lot of extra green light being reflected onto the person. By simply reducing the surface area and placing the person in the proper location, you can eliminate most of the green spill and color cast. In particular, having a green floor in front of the person is the most problematic setup issue that causes green spill. The floor will bounce green light onto the front of the person.
Green Screen Setup Guidelines
Only use as much green as you need - Extra green doesn't serve any purpose other than converting white light into green light. When white light from your strobes reflect off of the green screen or floor, it then becomes green light.<
You DON'T need to cover the entire frame with green - A lot of people think they are saving time by using large green screen set ups to ensure that they are covering the entire frame with green. The thought is that this will save time by eliminating the need to crop. However, by doing this, you may add time into your processing if you are adding green spill. Cropping the photos takes just a few seconds per image. If you shoot a bunch of images with green spill then it may cost you a lot more time trying to figure out the best spill correct settings in EZ green Screen. In extreme cases of spill, you may then need to manually touch it up which takes far more time than simply cropping the image. If you do insist on covering the entire camera view with green, then make sure to use as little extra screen as possible.
DON'T use a green floor unless you need one - If you are not putting feet into the final composition the don't stand the person on top of the green screen. A green floor in front of the person is the worst culprit for causing spill. This is because the green light is reflected onto the front of the person. If you are putting feet into the image the only have a few inches of floor in front of the feet. This will eliminate any spill except for a little bit on the feet.
Spill Comparison – Large vs. Small Green Screen Setups
The following simulation were done using 3D rendering software as shown in the video. The reason for this is to be able to easy change the settings to show how spill reacts with different screen configurations. Also, this allowed me to use solid white for the entire person. White is “worst case” for green spill and color cast issues so this was a way to really show the effects. The Blender 3D software can be used for photo realistic rendering and the lighting closely mimics real world lighting. Even thoug these are “cartoon” renders, the green spill shown closely represent real world green screen photography.