Quote:
Originally Posted by Pete Deksnis
Me too... As I saw it, there was a softness in the mono channel (probably from all the needed subcarrier filters?) and a general overall 'contrasty' look as though the brightness control on the TV could use a tweak upward.
|
I clearly remember the difference in rendition between B&W programs and color programs on B&W sets too. [After I learned about the color subcarrier, I realized you could see it as crawling dots if you got up close to our 21" B&W set at home too.]
The big difference was that the color cameras were never deliberately operated above the knee of the image orthicon, while B&W cameras were practically always operated above the knee.
Operation above the knee compressed the highlights, giving a very approximate gamma correction, but at the same time it redistributed the electrons from the highlights to the surrounding areas - this had an effect like the early Xerox copiers, where edge contrast was emphasized, but large dark areas tended to get washed out. This would have been horrible in a color camera, because a bright colored object would get a dark halo of a complementary color. I remember seeing some cases where a woman's red dress did over-expose the red channel, causing a cyan halo that covered her face - not pretty!
So, the color cameras were operated below the knee, and a gamma correction circuit was used to complement the picture tube gamma. However, you didn't get the super edge contrast enhancement. Also, the cameras were just barely acceptable for noise, and full gamma correction would have made it intolerable - so the cameras had partial correction, and the black level would have to be pushed up a little to make sure the picture was not too dark. This was a tricky matter of taste, because it also washed out the shadows a bit. The noise itself would also be partially rectified and result in obscuring the shadows. The true linear contrast range of a TK-41 driving an original light-faced CRT with any light in the room at all was probably only 20:1, whereas modern video systems can reach contrast ratios of several hundred to one, and without the picture looking too dark.
So - the appearance of video made with TK-41s is enhanced on a modern display; and the appearance of a vintage TV set is enhanced by playing modern video.