Colour Temperature

Colour temperature is a measure of the amount of various colours in a continuous spectrum of light. It is expressed in the Kelvin scale of temperature where 0°C is equivalent to 273 K.

Daylight is commonly perceived as being white although it actually always has a predominant colour present depending on the time of the day or the weather. In addition, artificial light is never white even though it may appear to be as the retinas in our eyes are highly capable of correcting for colour casts. Photographic film is unable to make this adjustment and therefore will only record what is visible hence suitable film must be selected for the particular light available.

If daylight balanced film is used in an environment that is lit by the common household bulb (tungsten light) then an orange colour cast will be recorded by the film. But if tungsten film was used in that same environment then the colours of the photograph would be as the naked eye sees it. For further details on daylight and tungsten balanced film and their suited applications, refer to the Colour Balance section in Film Characteristics.