I have a situation in which I own four high quality spectrophotometers.
Recently, I used each device to measure a particular paper-white.
Predictably, I received four different measurement results.
The deltaE between any two devices ranged from .47 to 1.73.
Unfortunately, I have no idea which of the four results is closest to the truth, and I do not know what the maximum difference between device results is reasonable.
Obviously, .47 is acceptable. And, we know from Steve’s last ColorNews article, that a deltaE < 1.0 could also be considered acceptable.
So, perhaps a deltaE => 1.0 should be considered suspect?
Finally, can anyone recommend a test kit containing calibrated materials that I can use to periodically check the accuracy of my spectrophotometers?