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Hi - I just joined the forum specifically to discuss this message:
"I also wonder too if the TK-40/41 halo'd a lot on a bright sunny day? I know it takes a fair bit of light to halo a TK-40/41 because of the colour filters allowing less light in the orthicons unlike a standard B&W orthicon. Anyhow it would be real interesting to see how good outdoor pictures look on one of those early cameras."
Before giving my opinion, a little backgroundon me so you can judge the source. I have been in the receiver electronics side of TV design for 38 years, and my principal responsibility at one time was video processing, which requried a good understanding of camera characteristics. I did not work directly with cameras/camera design, although I had to follow the technology.
I presume the question refers to the dark secondary-emission halo around highlights above the "knee" of the transfer characteristic in the image orthicon. I don't think this would have much to do with outdoor vs. indoor use, as it's not the filters in the color camera that prevent going over the knee, but deliberate reduction of exposure and use of special imo's that have a higher knee. Thus, the greatest problem in outdoor use wouldn't be the gross exposure level, but the uncontrolled contrast range of natural subjects and lighting.
In the studio, contrast range could be controlled to a degree by using gray or blue shirts instead of white, controlling the contrast range of sets and lighting, etc. Nevertheless, there was a squeeze between having adequate flesh tone exposure and keeping highlights below the knee. I remember seeeing occasionall cases where a bright red dress would have a cyan halo (very unflattering to the actess's face), while the rest of the scene was under control.
Part of the problem was that the imo is a fairly noisy device by today's standards, and therefore an extra gain boost to the lowlights and midrange for pleasing reproduction while keeping highlights below the knee was not possible.
Current cameras have excellent dynamic range, making it possible to "see into the shadows" to a degree the imo cameras could not achieve (maybe better with 4-tube cameras).
I don't remember seeing outdoor problems that were especially bad compared to the studio, but you have to realize that the changeover to plumbicons was fairly early in my career. That said, I remember local baseball games on WGN Chicago as having some of the best color video of the day. Of course, I would love to compare images directly to see the difference between imo's and today's cameras, and to recalibrate my memory. Maybe one of the collectors restoring TK-41s will give us that opportunity soon.
A major problem with the TK-41 pictures that I do remember clearly is registration failure. It was annoying even on a black and white set because of the strong color-subcarrier dot pattern that would appear on horizontal edges. You could almost count on one camera being out of register in any multi-camera parade broadcast.
Excuse the long-winded reply, please!
old_tv_nut
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