Lighting can be used to add mood and drama to a shot, but it also allows you to describe 3D objects onto a 2D space.
The Standard 3-Point Lighting Technique
The Three Point Lighting Technique is a standard method used in visual media such as video, film, still photography and computer-generated imagery. It is a simple but versatile system, which forms the basis of most lighting. Once you understand three point lighting you are well on the way to understanding all lighting.
Key Light
The Key light is the main source of illumination. It is usually the strongest and has the most influence on the look of the scene. It is placed to one side of the camera and subject so that the main features of the subject are highlighted, and the opposite side is shaded.
Fill Light
This is the secondary light and is placed on the opposite side of the key light. It is used to fill the shadows created by the key. The fill will usually be softer and less bright than the key.
Back Light
The back light is placed behind the subject and lights it from the rear. Rather than providing direct lighting (like the key and fill), its purpose is to provide definition and subtle highlights around the subject's outlines. This helps separate the subject from the background and provide a three-dimensional look. The backlight is also referred to as a rim-light or kicker.
The addition of a fourth light, the background light, or Set Light, makes for a four-point lighting setup. The background light is placed behind the subject(s), on a high grid, or low to the ground. Unlike the other three lights, which illuminate foreground elements like actors and props, it illuminates background elements, such as walls or outdoor scenery. This technique can be used to eliminate shadows cast by foreground elements onto the background, or to draw more attention to the background.