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Black And White Technology

N

notalkallstatic

I’m a big fan of B&W TV, but have always wondered, and tried to figure out: Why when a camera back from the early years of television had a light shined into it (like maybe they panned up to much, and a studio light got into the shot) it turned black instead of white?

Also, in the early years of color TV, why did it seem like, if there was a fast pan, or the colors on the set or colors of the clothes were too bright they would bleed? (Note, I know even today, extremely bright red bleeds, but back in the early day, it seemed a lot of colors bled.) I really noticed this with the Carol Burnett Show.

Why is this???
 
The black image was due to the camera tube being overloaded. Beyond a certain point, the equipment just could not pass the voltage of the video signal, and it would return to zero potential, or black, when that voltage ran too high.

The bleeding colors occurred because the contrast ratio of a color broadcast was typically in the 60% range...meaning that the light intensity only worked well in a very limited range. When the subject matter or light source strayed above that range, borders between different color areas would blend into one another. When the subject matter or light source strayed below that range, detail was lost in the darkness.

For comparison, Black-and-White television had a contrast ratio of about 70%. You could see much more detail of an image on a Black-and-White monitor than you could a color monitor. That's why, until fairly recently, most control-room monitors in television stations were Black-and-White, even though the station broadcast in color.

That is one reason that really dark-skinned people tended to be steered away from being on-camera. Fortunately, that is less of a problem since modern CCD cameras have 80%+ contrast ratios.

Later....
Matt Smith, Station Manager
WGSR-TV, Reidsville, NC
 
Matt, I noticed one good example when watching CBS's 25th anniv. special on JFK's assassination in 1988. At one point, they showed a closeup of the freshly-lit eternal flame at Arlington, and the flame pretty darn near appeared to be burning a hole in the screen.

ixnay
 
notalkallstatic said:
Why when a camera back from the early years of television had a light shined into it (like maybe they panned up to much, and a studio light got into the shot) it turned black instead of white? Why is this???
Click to expand...

I've noticed this too. It also happens when studio lighting is reflected into the camera lens off of something reflective, like a watch, a lens of someone's glasses, even light reflected off of a tie clip, I've seen make that area of the image go dark for a fraction of a second. I guess you could call it "video distortion."

Matt Smith said:
Black-and-White television had a contrast ratio of about 70%. You could see much more detail of an image on a Black-and-White monitor than you could a color monitor. That's why, until fairly recently, most control-room monitors in television stations were Black-and-White, even though the station broadcast in color.
Click to expand...

Which I'll bet is also why TV camera viewfinders are B & W, not color? Very interesting.
 
Matt Smith said:
The bleeding colors occurred because the contrast ratio of a color broadcast was typically in the 60% range...meaning that the light intensity only worked well in a very limited range. When the subject matter or light source strayed above that range, borders between different color areas would blend into one another. When the subject matter or light source strayed below that range, detail was lost in the darkness.
Click to expand...

Would that be the cause of why in the movie A Christmas Story that the red lights on the tree bleed over more and seem to be brighter than the other lights? I know that it's a film, but it's something I've wondered about over the years.
 
Matt, I noticed one good example when watching CBS's 25th anniv. special on JFK's assassination in 1988. At one point, they showed a closeup of the freshly-lit eternal flame at Arlington, and the flame pretty darn near appeared to be burning a hole in the screen.
I remember that happening a lot when someone wore an outfit with a lot of sequins or other shiny stuff on live or kinescoped black and white TV.
 
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