Colour temperature

From Nikonians Wiki

Colour temperature describes how blue or yellow a light appears. The human eye adjusts to differing Ambient Light, but a sensor cannot do this, so the white balance has to be set either automatically by the camera, manually by the photographer, or, for Raw shooting, afterwards in postprocessing.

Colour temperature is measured in Kelvin (K), which refers to the theoretical temperature of an ideal black body would have to be raised to in order to achieve a particular colour.

Note that fluorescent light does not have the same shaped spectrum as a black body light. Typically, fluorescent lights have a different tint as well as a colour temperature.

Note also that incandescent lights have a different colour temperature depending on their power. So, mixing 100 watt incandescent lights with 40 watt will produce differing colour temperature.

Generally speaking, except for natural light, which the eye accepts, mixing different colour temperatures in the image will create an unnatural impression. Mixing fluorescent with other types of light will tend to give a green cast to the image. It is virtually impossible to eliminate this in postprocessing.

Typical colour temperatures for mid-latitudes are are:

12,000 - 20,000 North Light (Blue Sky)

8,000 Average summer Shade

7,100 Light summer shade

6,500 'White' on a CRT screen for NTSC or PAL TV, typical summer light (sun + sky)

6,400 xenon short-arc

6,300 'daylight' type fluorescent light (not general consumer or commercial fluorescent light)

6,000 Overcast Daylight

5,900 Clear mercury lamp

5,500 Normalised reference light

5,400 Noon sunlight, electronic flash bulbs

5,200 white fluorescent (but note that there will be a green tint)

5,000 Horizon daylight, high colour rendering fluorescent

4,800-5,000 Daylight photoflood

4,300 early morning or late evening light

4,100 Moonlight

3,500 Golden hour one hour after dawn or before sunset

3,400 photoflood, studio continuous lighting

3,200 professional tungsten photographic lights

3,000 100 watt tungsten halogen

2,950 warm white fluorescent

2,870 100 watt incandescent

2,500 40 watt incandescent

2,100 Sodium light

2,000 Sunrise and sunset

1,850 Candle flame

1,700 Match flame

• This page was last modified on 11 January 2009, at 15:10.
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