Lighting technique and aesthetics

Background light - The background light is used to illuminate the background area of a set. The background light will also provide separation between the subject and the background. In the standard 4-point lighting setup, the background light is placed last and is usually placed directly behind the subject and pointed at the background.

In film, the background light is usually of lower intensity. More than one light could be used to light uniformly a background or alternatively to highlight points of interest.

In video and television, the background light is usually of similar intensity to the key light because video cameras are less capable of handling high-contrast ratios. In order to provide much needed separation between subject and background, the background light will have a color filter, blue for example, which will make the foreground pop up.

Cameo lighting - Cameo lighting in film is a spotlight that accentuates a single person in a scene. It creates an 'angelic' shot, such as one where God is shining down and a light shines down onto this person.

Cameo lighting derives its name from the art form in which a light relief figure is set against a darker background. It is often achieved by using barn-doored spotlights. It helps focus on the subject and not its environment. A problem with cameo lighting is that it can lead to color distortion and noise in the darkest areas.

Fill light - In television, film, stage, or photographic lighting, a fill light (often simply fill) may be used to reduce the contrast of a scene and provide some illumination for the areas of the image that are in shadow. A common lighting setup places the fill light on the lens axis, roughly perpendicular to the key light.

The fill light is often softer and, by definition, less intense than the key light. The ratio between light and shadow depends on the desired effect. For example, a fill light that is a small fraction of the power of the key light will produce very high-contrast or low-key lighting, while filling with half or more of the key light power will produce a high key, low-contrast tone.

An alternative to using a direct light source as a fill is to re-direct or "bounce" the key light towards the subject by using a reflector.

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 suggest an upbeat mood. It is often used in sitcoms and comedies. High-key lighting is usually quite homogeneous and free from dark shadows. The terminology comes from the key light (main light).

In the 1950s and 1960s, high-key lighting was achieved through multiple light sources lighting a scene—usually using three fixtures per person (left, right, and central) —which resulted in a uniform lighting pattern with very little modeling. Nowadays, multiple hot light sources are substituted by much more efficient fluorescent soft lights which provide a similar effect.

The advantage to high-key lighting is that it doesn't require adjustment 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 by lighting certain parts more prominently than others.

Most recently, shows with bigger budgets moved away from high-key lighting by using lighting set-ups different from the standard three-point lighting. Part of the reason for this is the advent of new lighting fixtures which are easier to use and quicker to set up. Another reason is the growing sophistication of the audience for TV programs and the need to differentiate.

The term "high-key" has found its way from cinema into more widespread usage, for example referring to an event that requires much organization or is subject to a great deal of publicity.

Key light - The key light is the first and usually most important light that a photographer, cinematographer, 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. The key light is not a rigid requirement; omitting the key light can result in a silhouette effect. Many key lights may be placed in a scene to illuminate a moving subject at opportune moments.

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. 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 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.

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, hence is commonly used in film noir and horror genres.

Ideas and Reflections:
There are some very interesting lighting techniques listed here but I have had the idea of using natural light for my film and filming out of focus lights.