Low-key lighting is a style of lighting for photography, film or television. It is a necessary element in creating a chiaroscuro effect. Traditional photographic lighting, three-point lighting uses a key light, a fill light, and a back light for illumination. Low-key lighting often uses only one key light, optionally controlled with a fill light or a simple reflector.
Low key light accentuates the contours of the subject by throwing areas into shade while a fill light or reflector may illuminate the shadow areas to control contrast. The relative strength of key-to-fill, known as the lighting ratio, can be measured using a light meter. Low key lighting has a higher lighting ratio, e.g., 8:1, than high-key lighting, which can approach 1:1.
The term “low key” is used in cinematography and photography to refer to any scene with a high lighting ratio, especially if there is a predominance of shadowy areas. It tends to heighten the sense of alienation felt by the viewer, hence is commonly used in film noir and horror genres.
In film, low-key lighting is associated with German Expressionism and later film noir.
Examples of low key black and white photography by fine art photographer Edward M. Fielding
Artists recognized the power of low key lighting long before photographers came around. Painters during the Renaissance and Baroque periods often used a technique known as “chiaroscuro” to achieve a similar dramatic tone for their images. Chiaroscuro comes from the Italian “chiaro” meaning clear/light and “oscuro” meaning obscure/dark.
Chiaroscuro was used not only for drama but also to bring realism to a painting. The varied lighting creates a sense of three dimensional depth that can be quite stunning.
Dark deep shadows and bright highlights require careful lighting techniques, exposure and intense post processing skills to achieve the dramatic look of low key photography.