HIGH-KEY LIGHTING
Excerpt from the Canon Boot Camp Manual
High-key lighting is often used in multi-camera sitcoms and comedies. It’s usually free from dark shadows so the boom mic above the actors doesn’t cast a shadow. Also, they don’t have to re-light for each camera’s viewpoint.
The advantage of high-key lighting is that it doesn’t require re-lighting for each scene, which allows the production to complete the shooting in hours instead of days. The primary drawback is that high-key lighting fails to add meaning or drama to the shot.
Low-Key Lighting
The term “low-key” is used in cinematography 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. It is commonly used in film noir and horror genres.