Portrait photography

Portrait photography or portraiture is photography of a person or group of people that captures the personality of a subject by using effective lighting, backdrops, and poses. A portrait picture might be artistic, or it might be clinical, as part of a medical study. Frequently, portraits are commissioned for special occasions, such as weddings or school events. Portraits can serve many purposes, from usage on a personal Web site to display in the lobby of a business.

The relatively low cost of the daguerreotype in the middle of the 19th century and the reduced sitting time for the subject, though still much longer than now, led to a general rise in the popularity of portrait photography over painted portraiture. The style of these early works reflected the technical challenges associated with long exposure times and the painterly aesthetic of the time. Subjects were generally seated against plain backgrounds and lit with the soft light of an overhead window and whatever else could be reflected with mirrors. Advances in photographic equipment and techniques developed, and gave photographers the ability to capture images with shorter exposure times and the making of portraits outside the studio.

When portrait photographs are composed and captured in a studio, the photographer has control over the lighting of the composition of the subject and can adjust direction and intensity of light. There are many ways to light a subject's face, but there are several common lighting plans which are easy enough to describe.

One of the most basic lighting plans is called three-point lighting. This plan uses three (and sometimes four) lights to fully model (bring out details and the three-dimensionality of) the subject's features. The three main lights used in this light plan are as follows:

Also called a main light, the key light is usually placed to one side of the subject's face, between 30 and 60 degrees off center and a bit higher than eye level. The purpose of the Key-Light is to give shape (modelling) to a subject, typically a face. This relies on the first principle of lighting, white comes out of a plane and black goes back into a plane. The depth of shadow created by the Main-Light can be controlled with a Fill-Light.

In modern photography, the fill-in light is used to control the contrast in the scene and is nearly always placed above the lens axis and is a large light source (think of the sky behind your head when taking a photograph). As the amount of light is less than the key-light (main-light), the fill acts by lifting the shadows only (particularly relevant in digital photography where the noise lives in the shadows). It is true to say that light bounces around a room and fills in the shadows but this does not mean that a fill-light should be placed opposite a key-light (main-light) and it does not soften shadows, it lifts them. The relative intensity (ratio) of the Key-light to the fill-light is most easily discussed in terms of "Stops" difference (where a Stop is a doubling or halving of the intensity of light). A 2 Stop reduction in intensity for the Fill-Light would be a typical start point to maintain dimensionality (modelling) in a portrait (head and shoulder) shot..

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Wikipedia