View source for 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 [http://en.wikipedia.org/wiki/Black_body Black body radiator] that exhibits that colour of light. Typical values are:

<cue table ripped from wikipedia>
{|border="1"
|-
! Temperature
! Source
|-
| 1,700&nbsp;K
| Match flame
|-
| 1,850&nbsp;K
| Candle flame
|-
| 2,700–3,300&nbsp;K
| Incandescent light bulb
|-
| 3,350&nbsp;K
| Studio "CP" light
|-
| 3,400&nbsp;K
| Studio lamps, photofloods, etc.
|-
| 4,100&nbsp;K
| Moonlight, xenon arc lamp
|-
| 5,000&nbsp;K
| Horizon daylight
|-
| 5,500–6,000&nbsp;K
| Typical daylight, electronic flash
|-
| 6,500&nbsp;K
| Daylight, overcast
|-
| 9,300&nbsp;K
| CRT screen
|- 
| colspan="2" style="font-size:x-small;" | ''Note'': These temperatures are merely characteristic;<br/>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 ==
* [http://www.leefilters.com/lighting/products/mired/ Lee Filters Mired Shift Calculator. Will suggest filters to you.] - This is the only way I've been able to get mired shift values from the Lee Filters website! ARG!
* [http://en.wikipedia.org/wiki/Mired Wikipedia on Mired]

[[Category:Lighting]]