Camera and Lighting Setup for a Chromatte Shoot
Before you start to light ensure the camera is set up as follows:
White balance preset or manual white balance
Setting the Camera’s White Balance
- Ensure the LiteRings are switched off
- Make sure there are no colored gels on your lights at this time
- If you are using dimmers to control your lights, while white balancing your camera, set the faders for your key light to 70% (all lights should be set to this nominal value for initial lighting).
- Focus the camera onto a reference white (a test chart/white paper)
- Light the white card evenly with your key light
- Use the iris to expose the card correctly
- Press the auto white button or select manual white balance from the menu
If for any reason you alter the white balance, go through the above process again ensuring the light you use does not have any colored gels on and that all other lights are switched off.
Setting Up the Lights
The lighting levels depend very much on the sensitivity of video camera you are using, however as a general rule you should be trying to light to between 500 and 1000 lux. This is typical of a 650w fresnel lamp flooded at approximately 15 feet from the subject. The use of a steep back light behind the subject illuminating the head and shoulders is also recommended. This light can be placed anywhere behind and above the subject but is normally placed on the same side as the key light to add both direction and separation to the key.
You should not attempt to illuminate the Chromatte, however any ambient spill onto the Chromatte will not be a problem at all. Do not place a key light directly above or on axis to the camera as the light from this lamp could dilute the effect of the Chromatte by creating a hot spot.
The distance from camera to subject will depend on the framing of the shot and the type of lens on the camera. Typically a distance of about 9-15 feet would be normal. At greater distances you will have to increase the LiteRing power or iris the camera open to compensate for the distances involved. The use of two backlights is optional, however tow do allow more control.
As far as subject to background distances are concerned, you do not need to leave large amounts of separation between subject and background as you would with traditional blue or green screen as there is no spill from the Chromatte curtain. Should you wish, you can place your subject flat up against the Chromatte curtain, however you may wish to leave a small gap (approx. 3 feet) to accommodate the back lights as suggested above.
- Set your lights to illuminate your subject based on lighting between 500 and 1000 max. (Your camera should iris at approx. f2.8 to f4, any higher than this and you may be using too much light)
- Switch the LiteRings on and set them initially to 50%
- Use your chromakeyer to get the best possible key
- Adjust the LiteRing slightly to compensate for errors
- Repeat the last two processes until you have satisfactory results
If your camera has a built in LCD display or your have a monitor, you can increase the LiteRing power until the blue or green starts to washout (you will see this as a slight color hue change on the monitor). Backing off the LiteRing until there is no color shift will give you a maximum setting.
If you are recording the foreground to tape for compositing in post, it is worth while initially testing the system to ascertain the best settings for the LiteRing. A short timed recording of your subject at several fixed LiteRing settings will provide a test for your optimum setting. Digitize this clip and note the setting that provides the best key.
Note: It is better to slightly overdrive than underdrive the LiteRing, but be careful not to get blue or green spill from the LiteRing onto the subject/talent.