Quote Originally Posted by Jorge Oliveira

- If you take the spectrum of an incandescent lamp and of a cold light source, they are quite different, but there are no different VC filters for each of these light sources, so maybe that's not a major issue.

Jorge O
A cold light does need a yellow filter of a some value I can't remember added to it to get in the proper range for VC filtration. Otherwise you have to calibrate and disregard the numbers on the VC filter and figure out the grade you are getting by comparing the results to graded paper.