On the subject of "variance of light meters", I just got one of my three Canon F1N bodys back after a C.L.A. before loading a film, and during checking it against the other two bodys with a Kodak Grey Card and a hand held light meter of known accuracy I was surprised to find that the bodys although manufactured about three years apart and me owning and using them for more than twenty years agreed with each other exactly, and the hand held meter, now to me that's impressive.