Points in Focus Photography

Mired/Filter Calculator

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Using the Calculator

To Calculate a Correction Filter

  1. Enter the film’s, or target lights, color temperature inĀ Color Temp 1.
  2. Enter the color temperature of the actual lighting in filed labeled Color Temp 2.
  3. Read the Mired value and choose a filter from the following table.
Cooling Filters Warming Filters
80A -131 85B 131
80B -112 85 112
80C -81 85C 81
80D -56 81EF 53
82C -45 81D 42
82B -32 81C 35
82A -10 81B 27
    81A 18
    81 9

E.g., if you have daylight balanced film (5500K), and you want to shoot with it in a tungsten interior (3200K) there’s a mired shift of -131, indicating you need a cooling filter of type 80A.

To Calculate the Mired Shift between two Lights

  1. Enter the color temp of the first light in Color Temp 2.
  2. Enter the color temp of the second light in Color Temp 1.
  3. Read the mired value:
  • A Positive mired value indicates the color shifted towards blue.
  • A negative mired value indicates the color shifted towards amber/orange.

E.g., if you have 2 light sources one is 5000K and one if 4000K, the difference in color from the first light to the second is 50 mireds.

Comments

Sid Bojangles

The source/target are mixed up in the calculator and I think the comments about negative being a shift toward warmer (and vice versa) are also backwards (well, once the other part is corrected). Or the cooling/warming filters chart is wrong? Anyway, it’s all mixed up. Please correct.

    Jason Franke  | admin

    Apologies for the confusion. I was trying to do several types of conversions using only a single form without adding any additional logic to it, and I think that may have been a problem.

    Mired values are negative when the shift is towards blue/cool and positive when the shift is towards amber/warm. The filter mired values were taken from published filter values, and are correct.

    I’ve tried to clarify the language. I’ve also put this calculator on the list of potential projects to update to be more usable.

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