Lighting is very important in photography, and this is especially true for chromakey work. It can be quite challenging. Here are three basic rules:
The photo at right is a great example of how to properly light your chromakey screen and subject. Notice how smooth the backing screen appears, and how visually distinct the model and screen appear.
This photograph was lit and shot by Wayne King of Peoria, AZ. Here is how Wayne describes his lighting setup and greenscreen photography process.
"For the screen, I rented a professional green backdrop from Photomark (the pro camera store in Phoenix that I use.) Total cost was $10.00.
"Two large soft boxes were placed about 3 feet from the backdrop and angled in about 45 degrees. Next, I took an incident meter reading to make sure the light on the backdrop was even over all but in particular around the area where the client's body was going to be. The meter reading was 125 @ F8.
"The client was placed 8 feet away from the backdrop. She was lighted with another large soft box from the right side (as you look at the picture). The angle was again about 45 degrees and slightly above her so that I would eliminate as much color spill as possible.
Then I placed a white reflector on the opposite side as a fill light. I choose this because I did not want to add more lights and therefore more spill possibility. I took a meter reading on the client's face and adjusted the lighting to 125 @ F11."
Many thanks to Wayne King for his expertise!
Other than our three suggestions above, there are no hard rules for lighting a chromakey shoot. The correct lighting depends upon how much room you have, what equipment you have, and what subject you are shooting. For instance, for little league shots, two umbrellas in front of the subject are adequate for consistent but flat lighting. For senior portraits, you might want a three-light setup to create moody or artistic lighting.
Light on background
You can light the background with separate lights if the background is too dark, since you don’t want the background blending into the subject’s shadow areas. However, you need to be careful about over-lighting and increasing the amount of spill. If you do light the background, you should plan on having the subject posed 8 to 10 ft away.
In most cases, avoid lighting the background. The more light on the background, the more spill you will potentially have. In most cases a couple softboxes and umbrellas do the trick nicely for lighting the subject and background. However, this strategy may not be feasible for large areas. If you are moving around and shooting from all angles then you may need to light the background.
Hair or back light
A hair or back light can give definition to the edges of the head. This can make it easier to separate the hair and reduce color spill on the shoulders. You usually want the background to be about a stop darker than your subject.
Be careful of lighting too bright as this can add a glow to the hair which looks fake when you remove the background. In general, we don’t recommend a back light. Too much risk of turning it into a big green light that is giving a green cast to your subject.
Light on floor
You can use a light on the floor pointing upwards to help minimize color spill on the legs and arms. If you’re doing a full length shot, you can use a floor light pointing down to help eliminate shadows on the floor. Caution: This will result in more light bouncing off of the chromakey floor onto your subject’s legs.
Magenta back light
If you’re getting a lot of green spill on the shoulders and arms, it’s also possible to use a magenta back light. This is sort of a last resort. It can help, but it’s tricky to use, as you don’t want to give everything a magenta cast. Giving your subject magenta shoulders instead of green ones won’t help you out much.
Another experienced photographer, Neal Martin, sent us this diagram of the lighting arrangement he uses for his chromakey work.
Neal says, "I photograph with a six light setup, in studio and location. Without getting into distance and power setups (which is dependent upon the background I've selected), basic things never change in photography. If you want it to look right, then photograph it right.
"Primatte is a wonderful plugin, but it will not correct a bad portrait session. You can't expect to stand your subject in front of a green screen and let Primatte take care of everything else.
"Your thinking has to change a bit. You need to look at the lighting on the background that has been chosen, then light the subject the same way such as light angle and contrast range. My dance magazine image was taken using this exact light setup."
It is important to research how to light your chromakey setup and position your model correctly. There are a lot of variables and it’s not always clear how they will come together. Our tips do not apply to every situation but they will give you guidance on the factors to look for.
Ultimately you need to do some experimentation. We recommend that you test your lighting and physical setup BEFORE you start photographing clients. There are many factors that can create a good or bad chromakey photo, and you will need to sort that out beforehand.
Step Six : Position the model