The key light is the first and usually most important light that a photographer, cinematographer

Cinematographer

A cinematographer is one photographing with a motion picture camera . The title is generally equivalent to director of photography , used to designate a chief over the camera and lighting crews working on a film, responsible for achieving artistic and technical decisions related to the image...

, lighting cameraman, or other scene composer will use in a lighting setup. The purpose of the key light is to highlight the form and dimension of the subject

Subject

-Philosophy:*Hypokeimenon or subiectum, in metaphysics, the essential being of a thing**Subject , a being that has subjective experiences, subjective consciousness, or a relationship with another entity...

. The key light is not a rigid requirement; omitting the key light can result in a silhouette

Silhouette

A silhouette is the image of a person, an object or scene consisting of the outline and a basically featureless interior, with the silhouetted object usually being black. Although the art form has been popular since the mid-18th century, the term “silhouette” was seldom used until the early decades...

 effect. Many key lights may be placed in a scene to illuminate a moving subject at opportune moments.

Position

The key light can be "hard" (focused) or "soft" (diffused), and depending on the desired setup can be placed at different angles relative to the subject. When part of the most common setup—three-point lighting

Three-point lighting

Three-point lighting is a standard method used in visual media such as video, film, still photography and computer-generated imagery. By using three separate positions, the photographer can illuminate the shot's subject however desired, while also controlling the shading and shadows produced by...

—the key light is placed at a 30–60° angle (with the camera

Camera

A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...

 marking 0 degrees). In addition to the horizontal angle, the key light can be placed high or low producing different effects. The most common vertical position for the key light is at a 30° degree angle (i.e. slightly above the eye line; the nose should not cast a shadow on the lips).

A key light positioned low appears to distort the actor's features, since most natural or ambient light is normally overhead. A dramatic effect used in horror or comedy cinematography

Cinematography

Cinematography is the making of lighting and camera choices when recording photographic images for cinema. It is closely related to the art of still photography...

 is a key light illuminating the face from below. A high key light will result in more prominent cheek bones and long nose shadows. Marlene Dietrich

Marlene Dietrich

Marlene Dietrich was a German-American actress and singer.Dietrich remained popular throughout her long career by continually re-inventing herself, professionally and characteristically. In the Berlin of the 1920s, she acted on the stage and in silent films...

 was famous for demanding that her key light be placed high.

Lighting a scene

Using just a key light results in a high-contrast scene, especially if the background is not illuminated. A fill light

Fill light

In television, film, stage, or photographic lighting, a fill light may be used to reduce the contrast of a scene and provide some illumination for the areas of the image that are in shadow...

 decreases contrast and adds more details to the dark areas of an image. An alternative to the fill light is to reflect existing light or to illuminate other objects in the scene (which in turn further illuminate the subject).

In addition to a key light, a back light may be added to "separate" the subject from the background. When the subject and/or camera are moving or turning around, the key light and back light may change roles.

The key light does not have to directly illuminate the subject: it may pass through various filters, screens, or reflectors. Light passing through tree leaves, window panes, and other obstacles can make a scene more visually interesting, as well as cue the audience to the location of the subject. The key light also does not have to be white light—a colored key (especially when used with fill/back lighting of other colors) can add more emotional depth to a scene than full white alone. In mixed indoor/outdoor daytime scenes, sunlight may appear to be a "warm" white, and indoor lighting to be a "neutral" or artificially-toned white. By contrast, moonlight appears to be "cooler" than indoor lighting.

Lighting choices

In many cases, the key light is a stage light for indoor scenes, or sunlight

Sunlight

Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...

 for outdoors. A lighting instrument may also be used outdoors to supplement sunlight or as the primary light source with sunlight or skylight serving as fill lighting. Actual lamp

Lamp (electrical component)

A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made...

s, lighting fixtures, can serve as key lights, provided they are of sufficient brightness. They may also appear within the scene as props — in which case they are called "practicals." Similarly, fire

Fire

Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....

, candles and other natural sources of light can be used.

See also

• High-key lighting
  High-key lighting
  High-key lighting is a style of lighting for film, television, or photography that aims to reduce the lighting ratio present in the scene. This was originally done partly for technological reasons, since early film and television did not deal well with high contrast ratios, but now is used to...
  
  
• Low-key lighting
  Low-key lighting
  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...
  
  
• Stage lighting instrument
  Stage lighting instrument
  Stage lighting instruments are used in stage lighting to illuminate theatrical productions, concerts, and other performances taking place in live performance venues. They are also used to light television studios and sound stages.Many stagecraft terms vary between the United States and the United...
  
  
• McCandless Method