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 Post subject: Re: Vintage BW studio cameras
PostPosted: Mar Sun 22, 2020 9:13 am 
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Location: Belrose, NSW, Australia
Well there's this at the ETF site:

http://www.earlytelevision.org/diamond_ ... #mar302019

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 Post subject: Re: Vintage BW studio cameras
PostPosted: Mar Sun 22, 2020 12:54 pm 
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Location: Annapolis, MD
Off-topic----but only a little bit:

If I am not mistaken, all of the early cameras sent on space missions used vidicons. I entered this scene in the late 60s when I went to work for NASA's Jet Propulsion Lab. One of my first assignments was testing the vidicons used in the Mariner missions to Mars, Venus, and Mercury. An interesting aspect of these systems was that the image tube was also the data storage buffer. With the available communication link, it took 42 seconds to transmit one picture from the spacecraft back to Earth. The trick was to store the image in the vidicon and then read it out VERY SLOWLY into the data system. These cameras were typically called "slow-scan".
For reasons long forgotten, the tubes were made by a small company in Texas whose principal product was truck scales.

The last US mission to use vidicon cameras was Voyager. On that project, a major problem with slow scan vidicons was solved: "Slow Scan" means low current, something that typical cathodes were not happy with. (The result was simply that the tube had a limited useful lifetime). Three engineers (2 from JPL, and one from the truck scale company) were awarded the Rank Prize for solving the problem for Voyager:
https://voyager.jpl.nasa.gov/news/detai ... icle_id=65

By the time I retired, I had spent enough time around electronic imaging systems, and was never inclined to pursue it as a hobby. I wonder if ETF has any of the early space hardware?

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 Post subject: Re: Vintage BW studio cameras
PostPosted: Mar Sun 22, 2020 11:45 pm 
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Location: Durham, NC
That little scale-making outfit in Texas is General Electrodynamics Company. Apparently its vidicon group was sold off sometime in the '60s, and the truck scale operation, profitable and self-sufficient, continued on with the old name to this day.

That "trick" of reading out a stored image on a vidicon's target was used by Hams in the '60s for slow-scan TV, using a system invented by 'Cop' McDonald in the late 1950s. The vidicon was biased for greatest lag when in regular fast-scan mode (used for aiming and focussing), then the lens was capped, putting the tube in darkness. The scan rate was then changed to a 120-line, 8 seconds/frame mode and the captured image was read off and transmitted. The very slow scan rate allowed transmission within a 3 kHz audio bandwidth. This was all-analog picture storage.

Regarding the Image Dissector (an early Philo Farnsworth invention), I worked for a couple years at Arvin Diamond Electronics, which had then only recently stopped making cameras that used those imagers. They found a stable, if small, market monitoring power plant steam boilers (Babcock & Wilcox was a big customer) using the rugged and simple, though insensitive dissector tubes. Light level was no problem, and since the tubes were non-storage types, there was no image retention -- important for reliable readings of water level in boilers. My boss had one of the tubes, but no cameras any more, alas, so I never got to see one working.

Richard Diehl ("LabGuy" on YouTube) has gotten at least one Image Dissector camera working, I believe.

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 Post subject: Re: Vintage BW studio cameras
PostPosted: Mar Mon 23, 2020 3:00 am 
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Joined: Nov Fri 30, 2012 3:35 am
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Location: Phoenix, AZ
Thank you for pointing out the article about image dissectors on ETF ... very interesting.
R/ John


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 Post subject: Re: Vintage BW studio cameras
PostPosted: Mar Mon 23, 2020 7:52 am 
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aj2x wrote:
That little scale-making outfit in Texas is General Electrodynamics Company. Apparently its vidicon group was sold off sometime in the '60s, and the truck scale operation, profitable and self-sufficient, continued on with the old name to this day..

I knew them well---In Garland, Texas--just outside Dallas

My memory was that JPL was working with them (GEC) all the way through the development of Voyager, which launched in 1977. If the group was sold off, I'm pretty sure it was after my last dealings with them--which was in the early 70s.

The other trivia bit is that the Vidicon operation came to GEC from Westinghouse (maybe that's what happened in the 60s??)

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 Post subject: Re: Vintage BW studio cameras
PostPosted: Mar Tue 24, 2020 1:17 pm 
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Location: St. Louis, MO, USA
Because of their ruggedness, image dissectors were also used to monitor nuclear tests back in the 50s and 60s.

Dennis


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