Light also has a temperature

You are here: Nature Science Photography – Lightness and color – The role of lighting quality

You have probably noticed that the midday light appears much whiter and more neutral than the rather reddish-warm late afternoon light. We can express this sensation physically in terms of color temperature, which is measured in Kelvin (K). High numbers of degrees mean a cool bluish tint, while low numbers mean warm, more yellow or reddish light. This may seem ludicrous at first, but it stems from the assumption that measuring color temperature involves a comparison with a specific metal body, commonly referred to as the „black body“. If you heat it up, it emits a reddish glow; if you heat it up further, it emits a blue-white glow. Depending on the temperature, it emits different colored light. At higher temperatures, the light is more bluish and thus appears colder to us. In practice, one does not usually calculate with Kelvin values but with the more handy Mired values (Micro Reciprocal Degree) or Dekamired values. They are derived from the Kelvin values according to the following formulas:

Mired = 1,000,000/color temperature in Kelvin.

Decamired = Mired/10

Some examples of color temperatures and their equivalent values:

Light definition       Color temperature	Mired		Delamired

Blue sky		12000 K			83		8
Normal daylight		5600 K			179		18
Incandescent lamp	3200 K			313		31
Candlelight		1500 K			667		67

Dekamired values for color films

Daylight film			18
Artificial light film 	3400 K	29
Artificial light film 	3200 K	31

Next Analog temperature correction

Main Lightness and Color

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