You want "Early Color"??? This is about as Early as it gets...

[old_tv_nut]

Originally Posted by ceebee23

It seems from all the reports and the recreated/restored equipment that CBS's field sequential system was capable of excellent results...the real problem was its incompatibility with existing sets.

I am not sure how flexible it was in operation switching between cameras etc.

And of course it would have migrated to all electronic pretty quickly.

The CBS system also benefitted from careful staging of every demo. I have a copy of a CBS technical memo describing problems with a bright red sweater, developing a cyan halo due to overexposure of the image orthicon. The solution was to substitute a darker sweater.

[colortel]

Originally Posted by old_tv_nut

The CBS system also benefitted from careful staging of every demo. I have a copy of a CBS technical memo describing problems with a bright red sweater, developing a cyan halo due to overexposure of the image orthicon. The solution was to substitute a darker sweater.

I also laughed at that solution. But I would think the CBS camera could have benefited from "Operating under the Knee", just as it was standard practice to reduce halos, and achieve linearity of the three primary signals with the later NTSC TK-41 cameras. The NTSC camera often suffered from poor balance between the IO's and the tubes were often hand selected to find three matching tubes. Reflections in the color splitting dichroics often led to "red shirt ghosts" image to the right of the gentleman's white shirt. This plus differential phase distortion with the NTSC signal, and camera and home receiver complexities of registration and adjustment, it is easy to say that the color reproduction of the CBS Color System was far superior. NTSC camers also benefited from careful staging and adjustment of the cameras.

Ask anyone who had seen demonstrations of the CBS Color System at the Early Television Foundation museum or any of the few monitors/receivers in the hands of collectors. The CBS system simply produced better color quality.

Ed Reitan

[dtuomi]

I understand that they used 405 lines for the CBS system so that the signal would fit into the 6mhz channel's that were already in use. What width did the channel have to be to use 525 lines with the CBS system? Understanding of course, that the refresh rate was different and that effects bandwidth usage as well.

David

[old_tv_nut]

Originally Posted by dtuomi

I understand that they used 405 lines for the CBS system so that the signal would fit into the 6mhz channel's that were already in use. What width did the channel have to be to use 525 lines with the CBS system? Understanding of course, that the refresh rate was different and that effects bandwidth usage as well.

David

the exact answer depends on a couple of things. CBS cheated on the horizontal resolution a bit, claiming that color helped distinquish objects, and also that the apparent sharpness would be good enough by using "crispening" techniques. Also, they reduced the frame rate to 24 frames per second (144 fields)

If you suppose 525 lines and 30 complete pictures per second, and the same horizontal resolution as black and white, the field sequential color would require 3 times the bandwidth as 525 black and white. The actual video bandwidth for black and white is 1.25 Mhz for the vestigial lower sideband, and 4.2 MHz for the upper sideband (total 5.45 MHz). The color case could also use 1.25 MHz for the lower sideband, but would need 3 x 4.2 = 12.6 MHz for the upper sideband. If the frame rate was reduced to 24 fps, this upper sideband would be reduced to 10.08 MHz.

DuMont produced some closed-circuit field sequential gear using 3 times the black and white rates.

See: http://www.earlytelevision.org/dumon...ial_color.html