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Colour temperature

Photopedia

18 October 2007 15:26

Colour temperature proves that seeing isn’t always believing. Our eyes tell us that all ‘white’ light is white, but in reality the colour of 'white' light varies according to the type of light source. This difference in the colour of light is known as colour temperature and is measured on the Kelvin (K) scale.

This scale ranges from a value of 12000K (the light from a clear blue sky) where the light is actually blue in colour. At 1900K (light from a candle), which is at the bottom of the scale, light is actually red. Digital camera sensors and film both record colour according to a preset colour temperature value.

Most colour films are balanced for 5500K daylight (midday sun), so when shooting in other light you’ll often need a colour correction filter to adjust for variation in the temperature. Digital cameras offer a white balance (WB) setting, which adjusts for each colour temperature.

In the days of film, correction filters had to be used when shooting daylight film under artificial light sources such as tungsten and fluorescent lighting. With digital photography, colour temperature relates directly to your shots in that you will set the white balance (WB), either in camera or at the RAW conversion stage. Here you can choose from a list of the most common presets, or even create a custom WB. To set a custom white balance you will need to shoot a white piece of card or something similar before setting your camera to read this as white. This custom WB will only remain accurate under the lighting conditions from which it was taken.