> Calibrated how is the $64K question.
Well, if delta EV between (L,a,b) (100,0,0) and (50,0,0) in total darkness is about 2 to 2.5 while (L,a,b) (100,0,0) is measured 8 to 10 EV than brightness is OK. Colour temperature and grey balance can be verified shooting grey patches of varying L displayed on the screen in Photoshop, out of focus, 1/15 of a second or slower, and checking colour temperature and uniformity of white balance for shots of different L in a raw converter. Only central portion of the patches should be used.
IMHO the issue at hand is more about colour management consistency.
For ISO =100:
EV = 2*log2(f) - log2(s); f is aperture number, s - exposure time in seconds.
For ISO 100, f/8, s=1/8 sec:
- log2(1/8) = 2*3 - (-3) = 9
Colorimeters and spectrophotometers are not always great at measuring light flux, while exposure meters are designed to do just that.