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-   Early Color Television (http://www.videokarma.org/forumdisplay.php?f=36)
-   -   21CT55 Screen-Shot Test (http://www.videokarma.org/showthread.php?t=257997)

Tomcomm 04-26-2013 02:56 PM

21CT55 Screen-Shot Test
 
Attempting to post full monitor screen size on VK Forum postings.

http://i677.photobucket.com/albums/v...1-2123_IMG.jpg[/URL]

http://i677.photobucket.com/albums/v...hots/Lama1.jpg[/URL]


http://i677.photobucket.com/albums/v...ps7e748ef5.jpg[/URL]


[http://i677.photobucket.com/albums/v...licker2010.jpg[/URL]

http://i677.photobucket.com/albums/v...pse3715511.jpg[/URL]

http://i677.photobucket.com/albums/v...psda96737b.jpg[/UR]

http://i677.photobucket.com/albums/v...ps7f8a985b.jpg[/URL]

zenithfan1 04-26-2013 03:05 PM

Hey Tom, that CT-55 has one hell of a picture on it.:thmbsp:

kvflyer 04-26-2013 03:46 PM

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!

Sandy G 04-26-2013 04:26 PM

"Glorious Lollipop Color"....(grin)

Username1 04-26-2013 06:28 PM

Nice job, very good picture.... good convergence!

me likey.....

sampson159 04-26-2013 09:48 PM

can you believe the saturation and the fleshtones?awesome pics.this is the pinnacle of real color tv.loving this!

Sandy G 04-26-2013 09:59 PM

Amazing picture, & it was done w/o all those hokey "Color Correction" circuits they had later..They HAD virtual HDTV in '54, they just didn't realize it..

ChrisW6ATV 04-27-2013 02:18 AM

Very nice screen shots!

The color "correction" circuits were really color "poor adjustment compensation" circuits. Ruin a good thing for the sake of making it "good enough for average, sloppy users". Way too much of the world is made that way, it seems.

Mal Fuller 04-27-2013 06:48 AM

What's wrong with this picture?
I remember that the CTC2B chassis sat flat in its cabinet and that the CTC4 chassis was the first to be mounted vertically as shown.

lnx64 04-27-2013 12:08 PM

Wow that third screenshot, looks so sharp and defined! I thought this was S-Video modified for a second.

Pete Deksnis 04-27-2013 04:10 PM

Loved the llama shot.

Pete

stromberg6 04-27-2013 06:04 PM

Beautiful pics as usual, Tom. Thanks for sharing!:yes:
Kevin

old_tv_nut 04-27-2013 09:08 PM

Quote:

Originally Posted by kvflyer (Post 3067717)
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!

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.

benman94 04-28-2013 09:28 AM

Would the 19VP22 be NTSC correct also? It was my understanding that they were, but I could be mistaken. That set is looking amazing Tom!
-Benny

kvflyer 04-28-2013 10:26 AM

Quote:

Originally Posted by old_tv_nut (Post 3067868)
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 . ...

Thank you very, very much for answering that question in great detail. I have a CTC-9 in queue for restoration. But it, as you must know, does not have the 21AXP22 in it, rather the 21CYP22. And, I hold no hope to ever have access to a 15GP22!

In reading this thread and the thread that was linked, it sure does bring back memories. I remember when color TV was a new thing. I just didn't remember the change in color. But I sure do know what you are talking about. I had a Heathkit GR-2000 (I think that is the number) that had a Zenith CRT in it. I always felt that the colors favored earthtones. I thought that it was similar to the 70s obsession with browns and oranges. No bright blues, greens or reds.

I also remember working for EJ Korvette. I worked in the Audio Dept. which was right next to what they called "Major Appliances". In that dept., they had a room with doors that had all of the color sets in it. It was a very dim room. Hmmm, there's a surprise! I just hope to one day have a set with the early phosphors in it.

Again, thanks for explaining and taking the time to search and post.


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