In television, film, stage, or photographic lighting, a fill light (often simply fill) may be used to reduce the contrast of a scene and provide some illumination for the areas of the image that are in shadow. A common lighting setup places the fill light on the lens axis, roughly perpendicular to the key light.
The fill light is often softer and, by definition, less intense than the key light. The ratio between light and shadow depends on the desired effect. For example, a fill light that is a small fraction of the power of the key light will produce very high-contrast or low-key lighting, while filling with half or more of the key light power will produce a high key, low-contrast tone.
In cases where the fill light is desired to be darker than what is available without artificial means, a flag or frame may be used to block ambient light and thereby provide what is called negative fill.
An alternative to using a direct light source as a fill is to re-direct or "bounce" the key light towards the subject by using a reflector.
Famous quotes containing the words fill and/or light:
“Help to bewail the woeful case
And eke the heavy plight
Of me, that wonted to rejoice
The fortunes of my pleasant choice.
Good ladies, help to fill my mourning voice.”
—Henry Howard, Earl Of Surrey (1517?–1547)
“There is no ill which may not be dissipated, like the dark, if you let in a stronger light upon it.”
—Henry David Thoreau (1817–1862)