Set up the chroma screen, typically a large green or blue screen that will serve as your scene's background, at the back of your set and props. Special effects will replace this background in production or post-production. Make sure that your chroma screen is at least 6 feet from the scene to be shot. The screen should be large enough to cover the entire background of the scene.
Set up your lighting equipment on the set. Make sure that the chroma screen is evenly lit. The main challenge for this type of setup is lighting your scene according to your creative requirements, which is different from the flat and even lighting of the chroma screen.
Create a lighting setup with one major source of light on one side. This will be the strongest light in the setup. Placing strong light under someone's face creates a scary look. Placing light at a canted angle can produce eerie shadows.
Use a fill light at another angle facing the main light. Its placement is generally opposite the main light, but its height, angle and distance relative to the scene depends on the location of the actor or object needing additional illumination. Incorrect placement can result in unintentional heavy shadowing or underexposure on the side opposite the main light. The fill light should be a diffused light that is more subtle in brightness and intensity than the main light. This softer light minimizes the shadows thrown by the main light.
Use a backlight and any additional light to add depth to the look of the scene. Such lights help guide the eyes of viewers to the desired focus of the scene. For example, certain lights can provide a highlight on the hair or the contour of the face or an object.
Add lighting equipment and other special effect devices to create more lighting effects or halos in elements in the scene. This equipment typically includes production lights including HMI lights, Fresnels, Redheads, Kino Flos and Dedolights. Varying in light intensity, brightness, size and electrical requirements, some of these lights are tungsten-based and resemble warmer lights such as those from shaded lamps and most streetlights. Some resemble sunlight. Reflectors and diffusers can consist of plastic foam that bounces softer lights onto your subject or a foil-like board with a large surface to reflect stronger lights from lighting equipment or sunlight.
Your lighting setup will also depend on how the background replacing the chroma screen would look. Your overall lighting setup should match the special effects to be placed on the background.
Prepare your basic lighting setup by placing each piece of equipment on the set. Position the camera at the intended angle and distance from the scene, then fix the lighting and grip equipment in places outside the intended film frame. Direct the lights in their intended locations.
Set up supporting lighting equipment. Cookies or flags are often placed on some lighting equipment to create shadows. These items are placed over the light's beam to alter the way the light falls on a scene. Cookies are generally black rectangular boards filled with smaller holes shaped like such things as leaves and tree branches. Flags are black rectangular boards that can cover certain parts of the light falling on the scene. One is used to control the light on an object that must be partly lit, with a portion that looks darker or is unlit.
A dimmer may be attached to the lighting equipment for better control of the brightness of lights. Other controls on the lights can create lightning or underwater effects.
Set up additional equipment and devices to complete the lighting special effects, including a smoke or fog machine, or a filter on the camera lens to make the scene's lighting look eerie or unnatural.