Quote:
Originally Posted by kvflyer
You know, I thought that as color television matured, the colors etc. would have improved exponentially. Obviously, I was wrong. I remember early color but didn't know about the differences.
What CRT has the "correct" colors, red especially and when did it change please? For instance, was the 15GP22 the only one with correct colors, or does a 21CPY22 have the same colors. I realize I skipped ahead by several steps.
Just wondering...
Thanks!
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See post #12 in this thread:
http://www.videokarma.org/showthread...color+phosphor
The only correct NTSC tubes were the 15GP22 and the early 21AXP22's.
The main difference that affected both greens and reds was the change from P1 green to sulfide green . The sulfide red was somewhat more orangy than other reds, but the rare-earth reds usually are quite close to NTSC red.
NTSC red, by the way, is a bit orange - it can reproduce car tail lights but not traffic signal red.
Also, when the NTSC blue, which is somewhat towards cyan, was replaced by more-violet sulfide blue, this affected flesh tones by moving yellows towards green.
This has been a mishmosh in NTSC for all tubes after the 15GP22 and 21AXP22, and only PAL and now HDTV have got it right by changing the cameras to match the modern phosphors. You can see "chery red" as distinct from other reds with the modern phosphors if the camera is designed for them. Otherwise, the approximate corrections built into NTSC sets result in overdriving the bright reds, making them all overly bright and the same color as the red phosphor.
Having a 15GP22 no longer guarantees you correct color on NTSC sources, since at the same time receiver manufacturers were putting in compensation, camera manufacturers were fudging to get acceptable pictures on monitors with the new phosphors and monitor manufacturers were including switchable matrices that could either demodulate straight (but with the modern phosphors) or with an electrical correction similar to home receivers.
This was like the factory time keeper blowing the whistle based on the train departure while the train conductor set his watch by the factory whistle.
The original TK-41 cameras had no matrixing to tweak, but relied on careful selection of trimming filters in each color channel to get the best response for NTSC phosphors. This was a major reason why their optics were so inefficient. Later versions had more efficient wider-passband prism optics, but still no matrixing, and the prism passbands were still optimized for NTSC phosphors. So at this time (early 60s) the futzing was all in the receivers. As soon as Plumbicon cameras appeared, they had to have matrixing because the deep red response was so poor; and the good signal-to-noise ratio of Plumbicons made matrixing possible without excessive noise. The receiver manufacturers had been playing with the color for some years, but now the camera designers were too. This is the point at which PAL standards were developed, so they had the option to make the receivers demodulate without special compensation and do the proper compensation for the new phosphors in the cameras.
NTSC countries were not so blessed, because they already had a population of receivers with various approximate compensation for the new phosphors.