Quote:
Originally Posted by Penthode
I was using a late 1940's 10BP4 as reference. It is has a lower color temperature as it is much less blue.I agree as I have seen how mid to late 50s monochrome CRTs do have a higher color temperature.
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That's great. I have definitely seen the difference in the older sets at the Early Television museum.
I have an I1 Pro3 spectrophotomter I use for calibrating my computer monitors, as the less expensive colorimeters I had in the past could not do a good job of matching different models of monitor.
This discussion prompted me to get out the Minolta spot colorimeter I got when Zenith closed down their lab in 2000. Its last calibration was in 1998. It is way off when measuring the two LCD computer monitors (Viewsonic with sRGB gamut and HP with wide gamut). These monitors match visually when calibrated to 5000 Kelvin with the I1, but measure 4000 to 4400 with the Minolta. So, I guess the Minolta suffers the same problems as other colorimeters even though it was an expensive top-of-the-line unit at the time.
I know the home-built colorimeters that Zenith used on the assembly line had to be recalibrated any time the phosphor formulation was changed. This was a long chain of calibrating a spectrophotometer (which used a photomultiplier tube at the time) using an NBS traceable incandescent lamp and then measuring a CRT with the new phosphors and calibrating the production line colorimeters to match those readings. I never talked to whoever was using the Minolta, so don't know if it required the same calibration procedure, but I suspect it did.