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:
“It is the characteristic of great poems that they will yield of their sense in due proportion to the hasty and the deliberate reader. To the practical they will be common sense, and to the wise wisdom; as either the traveler may wet his lips, or an army may fill its water-casks at a full stream.”
—Henry David Thoreau (1817–1862)
“Dear friend,
I will have to sink with hundreds of others
on a dumbwaiter into hell.
I will be a light thing.
I will enter death
like someone’s lost optical lens.”
—Anne Sexton (1928–1974)