Kintatsu: I believe you're correct. I recall reading about the 12% vs the 18%. But of course, that begs the question. If the meters are set for 12% standard, of what value is using an 18% gray card? Shouldn't we be using a 12% gray card so our reflective and incident readings will match? Does anyone make such a thing?

E. von Hough: Have you actually tried 18% gray card measurement and incident readings with the Luna Pro in the same light? Do you get the same readings? If so, it appears then that your meter is calibrated to the 18% reading not the industry standard 12%.