"Low-key lighting (or ambient lighting) is a style of lighting photography It attempts to create a
chiaroscuro effect. In traditional photographic lighting, three-point lighting uses a key light, a fill
light, and a back light for even illumination. Low-key lighting requires only one key light,
optionally controlled with a fill light or a simple reflector.
Low key light accentuates the contours of an object 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."
"Chiaroscuro (kiːɑːrˈə.skʊrˈoʊ, –skjʊrˈoʊ, Italian for light-dark) in art is contrast between light
and dark, usually bold contrasts affecting a whole composition. It is also more technically used
by artists and art historians for the use of effects representing contrasts of light, not necessarily
strong, to achieve a sense of volume in modeling three-dimensional objects such as the human
body." from Wikipedia
Low Key lighting is typically used to show drama or a strong mood in an image. I use it a good
bit in photographing artistic nudes. The Low-Key effect shows off the contours of the human
body and brings drama to a photograph.