Mired Shift

What is Mired Shift?

Mired is a measurement of colour temperature. Mired shift is a change in this value. Colour correction filters have a specific mired shift value (e.g -71). Colour temperature is defined as the temperature of an equivalent Black body radiator that exhibits that colour of light. Typical values are:

<cue table ripped from wikipedia>

Temperature Source
1,700 K Match flame
1,850 K Candle flame
2,700–3,300 K Incandescent light bulb
3,350 K Studio "CP" light
3,400 K Studio lamps, photofloods, etc.
4,100 K Moonlight, xenon arc lamp
5,000 K Horizon daylight
5,500–6,000 K Typical daylight, electronic flash
6,500 K Daylight, overcast
9,300 K CRT screen
Note: These temperatures are merely characteristic;
considerable variation may be present.

</cue table ripped from wikipedia>

Why is it useful?

Knowing the mired shift you need allows you to select a filter to convert from any colour temperature to any other colour temperature. It means you are not limited to the standard conversions such as "tungsten to daylight" - especially as daylight can take many different values.

Another case where calculating the mired shift is useful is when you have a scene involving a lit candle and you want to simulate the light it gives off with a tungsten fixture. (this is a mired shift of +228 and the lee filters calculator suggests full C.T straw together with 1/4 C.T straw to give +202)

How do I calculate it?

<math>Mired Value = \frac{1000000}{Colour Temp}</math> and the shift is (temp wanted)-(temp we have) so:

<math>Mired Shift = \frac{1000000}{Colour Temp wanted}-\frac{1000000}{Colour Temp we have}</math>

so for the above tungsten to candle example:

<math>Mired Shift = \frac{1000000}{1850K}-\frac{1000000}{3200K}</math>

<math>+228 = \frac{1000000}{1850K}-\frac{1000000}{3200K}</math>

Mired shifts can be both positive and negative depending on if we are increasing or decreasing the colour temperature (+ decreases, - increases) To put it another way, positive shifts add orange, negative shifts add blue.

Other useful links