Use of light can make or break a picture- it is thus an important consideration for photographers. In order to fully use the light, a photographer needs to have a basic knowledge of how eyes and lens perceives colour spectrum.
Spectrum of colours
Natural sunlight and incandescent artificial light appears white to the naked eyes. A white light splits into rainbow of colours when passed through a prism. Therefore, the white colour contains every shade in the colour spectrum. When a light falls on an object, it absorbs a portion of it and reflects back the some of the colours. The portion of colours that is reflected back is the colour of the object which appears to the human eyes.
At different times of the day, different hues of the colour spectrum is dominant. At midday, the blue shade is most prevalent which help to produce clearest picture. The natural light during sunrise and sunset emphasises red portion of the colour spectrum. These warm light help to produce pictures with a softer contrast,
Artificial lights used in photography
When photographers use artificial lights, the effect of lights depends on the kinds of bulbs that are used. The incandescent lights produces warm dispersed glow that is starkly different from that of narrow focus beam of a street light.
Photographs taken using incandescent lights often appear yellowish. This effect can be minimised in two ways. You can either use blue filter to offset that yellow tinge or make use of film camera in place of digital one. In film camera, you can use tungsten films that are specially designed for professional studio lights. Though, the tungsten films are not designed keeping in mind the incandescent lights, it is often observed that in in indoor coloured photography tungsten films reduceyellowish tones.
Aneminent problem that photographers faced with the usage of florescent lights is that a greenish tinge appears on the pictures. However, this greenish effect can be minimised using a daytime or florescent filter. The photographers may use the greenish effect for their advantage. When used in darkness, the greenish quality can produce eerie and mysterious effects.
Direct and diffuse light in photography
Different angles of light cast shadows at different positions completely changing the appearance of the subjects. Lights in the photography may be diffuse or direct. If you have the intention to show a contrast between light and shadow, it is a good choice to use direct light.
Diffuse lights on the other hand, hit subjects from different angles. These lights reduce contrasts, soften images and mute colours.
Black and white or colour photography?
While lighting is imperative for coloured photography, it is even more essential for black and white or sepia photography. The main attribute of black and white photography is the contrast between light and shade. The basic rules on the use of lights in photography remain same for both the genres. However, as the contrast of light and shadow is more eminent in black and white photography than the coloured ones, the photographer must opt for direct lights while composing the shots.