I've been blessed!

[old_tv_nut]

Originally Posted by Penthode

I try to clolor balance the black and white image against a black and white television of the era. If you had a colorimeter you could do it more accurately but in those days, especially with color drift as the set warms, I find eyeballing it against a P4 phosphor television is the best you can do.

I do have a colorimeter, but I usually balance by eye against natural light coming in the window. I haven't tried measuring the CTC-5 for a long time, but using my DSLR as a rough colorimeter, it measures somewhere around 7700 to 8000 Kelvin as set by eye. I think many/most P4 tubes from the early/mid 50s onward were far too blue as a color set reference. I seem to recall GE boasting how blue their P4 tubes were.

[Penthode]

Originally Posted by old_tv_nut

I do have a colorimeter, but I usually balance by eye against natural light coming in the window. I haven't tried measuring the CTC-5 for a long time, but using my DSLR as a rough colorimeter, it measures somewhere around 7700 to 8000 Kelvin as set by eye. I think many/most P4 tubes from the early/mid 50s onward were far too blue as a color set reference. I seem to recall GE boasting how blue their P4 tubes were.

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.

[old_tv_nut]

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.

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.