Three point lighting

One of the most decisive factors creating the visual mood through lighting is the question of contrast and light distribution known as Low Key and High Key styles. These styles should not be confused with hard and soft lighting, though there are many parallels and similarities.

In a Low Key scene the majority of the picture is underlit, but some parts are correctly exposed or even overexposed. Underexposing all the areas would lead to a murky picture without sufficient contrast and visual impact. By comparison of brightness and shadows that our eyes comprehend, the lighting values in the frame.

High key represents the opposite concept. Here most of the frame is well lit with lot of soft fill light. Sets are rather light in color. If the heavy shadows of Low Key are intended to introduce an element of suspense, the shadowless High Key leaves nothing to the audience’s imagination.

But to understand High Key and Low Key styles, first must take a closer look at the character and the functions performed by light in a scene, best illustrated by the 3-Point Lighting Technique.  This formula is a sort of starting point for lots of variations and you see it a lot on TV, but often a network news crew will even take the trouble to set up 3-point lighting in awkward field situations.

The Three Point Lighting Technique is a simple but versatile system which forms the basis of most lighting, and naturally you will need three lights to use this formula. The basic procedure is as follows:
  • Start in darkness. Make sure there are no default lights, and there's no global ambience. When you add your first light, there should be no other light in the scene.
  • Add the key light, to create the subject's main illumination, and to define the most visible lighting and shadows.
  • Set the fill light to illuminate shadowed areas and to soften and extend the illumination provided by the key light.
  • Set a backlight to create a bright line around the edge of the object and to separate the subject from the background.

Key light

This is the main light, which gives character to the scene. It is placed at a thirty to forty-five degree angle in front of the subject and to the side of the camera to provide some modeling. The light is positioned above the subject, but not too high, in order to shine into the face of the subject.

Fill light

This is the secondary light, usually the same height, and it is placed on the side of the camera just opposite of the key light. The fill light is a very important light, is set to about half the intensity of the key light, and it’s main purpose is to soften shadows created by the key light. If using only a 2-light system, a reflector can be used to bounce light back onto the subject, to ensure that no hard shadows are cast on the subject.

Back light

The back light is placed behind and sometimes above the subject, pointed at the back of the head and shoulders. Back light fulfills the function of separating people from the background, providing a three-dimensional look.

Some more radical cinematographers reject back light altogether as artificial but with the advent of softer key light the majority of cinematographers find back lights very useful.

Depending on the angle these accentuating, textural lights have many names. Back light usually means a light directly behind the subject, in line with lens. A back light that does not indicate the source but just lights the hair is appropriately called the hair light.  Also from the back comes the rim light which gives just a thin rim of light to the subject. The next light farther to the side is the kicker, which gives a certain sheen to the cheek as seen from the camera position. Farther yet to the side is a liner, which could be defined as a kicker, but is forward enough so that it does not produce any sheen. Glow light comes more from the side and basically creates a little glow on the shadowy side of the face but does not produce any shadows of its own.

This is a systematizing of these terms, but in practice they are used less precisely and sometimes interchangeable. Various cinematographers and gaffers develop their own terminology over the years.