This is the first meter to read the spectral sensitivity of color film, CDCD (CCD) and CMOS sensors used in current digital still and DV cine cameras.
The C-500R color meter is not a exposure meter. Their main function is "pre-production" light source color control. With all the emphasis on Color Management and Workflow done electronically and in the camera or in post production, today's digital photographers seem to have overlooked the first step and foundation of the whole process, namely the light that makes image creation possible.
Custom white balance can do a good job of correcting color for a single light source. Add another, and there will be an unbalance that will cause color problems that will have to be dealt with later at a cost of time and money. In mixed light sources, blending flash with ambient (sun or indoor whatever) can be "cleaning up the color by adding some flash" which is the norm today. Or, with the C-500R and a little light source filtration, it can be the seamless blending of illumination to make the photographer-added light virtually undetectable as it was done by photographers who "knew how" in the good old days of film.