By how many degrees Kelvin is the color temperature increased when using a Portrait ExpoDisc versus a Neutral ExpoDisc?
The color temperature increase is approximately equivalent to adding an 81A filter to your camera after you set a neutral white balance. An 81A filter introduces a color adjustment of +18 mireds (micro-reciprocal degrees). To determine the exact color temperature shift you will need to know the color temperature of the light falling on your subject. Example: If you are shooting a subject under lights balanced to a color temperature of 3400K and you add an 81A filter, the resulting picture will appear as if it was photographed using lights balanced for 3200K. (Note: This was a common situation when using film balanced for 3200K [Type B] and you were shooting with lights balanced for 3400K [Type A].) The change in the color temperature is 200K. Using the following table you can do the calculation: 1. Find the Reciprocal Color Temperature for 3400K (294 mireds) 2. Add 18 to this number (294 + 18 = 312) 3. Locate the number 312 in the table and read the color temperature (3200K). 4. 3400K
