The Mired value concept

The shift in color temperature can be expressed as a ratio based measurement, called mired. Below I have supplied a nomogram on how to determine the mired shift value. What you need to know are two parameters:

  • The color temperature of your light source, on the left of the nomogram
  • The color temperature rating of your film material on the right of the nomogram

    If you connect the two points with a straight line, then the intersection in the center will give you the reading of the mired shift value. In the example provided I assumed you take a photograph with a photoflood lamp rated at 3200 K on a daylight film material rated at 5500 K. The red line intersects at a mired shift value of -130. On the left of the center column you find the indication "80A"; it refers to the commonly used Kodak Wratten filters. The most commonly encountered filters are listed on the nomogram for easy reference. Note, however, that if you, e.g. try to use an indoor general purpose light bulb of 40 W rating on a daylight film, then you will not find a listed Kodak filter. Here you have to refer to the mired shift value and ask in a store for a filter with that particular characteristic. You will have to check with a store catering to the professional photographers, and may still have to search for a knowledgeable person; however, if you have found someone who is conversant in mired, you will have found someone who knows his/her field.

    mired nomogram