Ambient Light

Ambient light is the illumination already present in a scene rather than supplied by the photographer, whether sunlight, skylight, and moonlight or the lamps, windows, and signs of an interior or street. In most usage the term is interchangeable with "available light" and "existing light," and all three are defined against light the photographer adds with flash or lamps. Working by ambient light indoors and at speed became practical with German miniature cameras fitted with wide-aperture lenses, above all the Ermanox of 1924, whose Ernostar lens opened to f/2 and later f/1.8, and the Leica of 1925. Erich Salomon used the Ermanox to photograph politicians and public figures at meetings closed to photographers, often without their knowledge, and illustrated weeklies in Munich and Berlin began printing this kind of unposed reportage in 1928 and 1929.

In practice, the photographer accepts the direction, intensity, and color the scene offers and adjusts the exposure rather than the light. Opening the aperture, slowing the shutter, or raising sensitivity each leaves a mark, whether shallow depth of field, subject blur and camera shake, or visible grain. Fast black-and-white emulsions such as Kodak Tri-X, introduced in 1954 at a rating of 400 and often push-processed beyond it, became standard for interiors, streets after dark, and fast-moving events, and their coarse grain came to read as part of the look. Color film records the actual color temperature of each source, so daylight-balanced stock under tungsten lamps turns yellow-orange, while tungsten film outdoors turns blue. In flash work, "ambient" also names the base exposure set by shutter speed, aperture, and ISO, which is often held slightly below normal so that the flash fills the difference.

Picture magazines made the choice a matter of editorial policy. Stefan Lorant's Picture Post encouraged available-light photography from 1938, and in 1945 Life hired Leonard McCombe on a contract that forbade him to use flash. Ambient light overlaps with Natural Light but is broader, since it includes artificial sources already in the scene, such as room lamps, street lighting, and neon. It contrasts with Flash, Direct Flash, and Studio Lighting, in which the photographer builds the illumination. It also overlaps with Low-Light, which describes how dim a scene is rather than where its light comes from.