The most basic lighting technique used in cinema is the three-point
lighting system. It was developed during the Hollywood big studio era and
is still widely practiced throughout the world.
Three point lighting creates a very natural, realistic look to the scene.
The primary light source, or key light, illuminates the dominant subject in
the shot. This draws the viewers’ eye directly to that point because it is
the highest point of contrast, usually of light and shadow. A
cinematographer sets the key light up to direct attention towards the
shot’s focal point of action, either psychological or physical. It is the
brightest light, usually positioned to illuminate the side of the person’s
face that isn’t directly facing the camera.
Fill lights, which are approximately half as bright as the key lights,
soften the harshness of the key light. This soft, diffused light, is often
bounced off a reflective umbrella, or shined through a sheet of diffusion
or softbox. This light is gentler on the subject than the key light, and it
fills in the shadows of the key light. It’s used to illuminate the side of
the face opposite the key light, and reveals subsidiary details that would
otherwise be hidden in shadow.
The third point of the three point lighting system is the backlight.
Backlights work to separate the foreground from the background, creating a
great depth of field. Without a backlight the image would appear very flat
and two-dimensional. These three lights are used together to create the
most realistic shot possible, and although seen as one of the most basic
lighting techniques, is still used in many major films today.