Kineskope frame rate

[DVtyro]

PDFs on your website are a treasure trove! So, the picture was "painted" on the master film by an electronic beam. Then copies were made by optical duplication. Then the picture was be scanned by an electronic beam again and converted to TV image. It is an interesting blend of analog electronics with film tech. I applaud that 60 fps was chosen to preserve as much info as possible.

Considering how magnetic tape, HDDs, memory cards age over time, maybe it makes sense to reconsider using film for long-term storage? Actually, I think optical discs are the best for long term, but I am very afraid that soon there won't be any CD/DVD/BD readers.

For black-and-white version, have anyone thought that the second track should start at the end of the film, so it would work like a regular audio tape: play track 1 from the beginning to the end, then switch to track 2 and play in reverse. This way you would get 50 minutes of moving picture with just a small blip in the middle.

[old_tv_nut]

Originally Posted by DVtyro

...
For black-and-white version, have anyone thought that the second track should start at the end of the film, so it would work like a regular audio tape: play track 1 from the beginning to the end, then switch to track 2 and play in reverse. This way you would get 50 minutes of moving picture with just a small blip in the middle.

That's an interesting idea, but it would require the extra complication of reversing the vertical scan of the flying spot as well as the mechanics of the player, so I guess Dr. Goldmark and the CBS crew didn't think it was worth the trouble.

In the player the film was pulled across the scanning gate by a capstan that was just after the gate and well before the takeup reel. It seems to me that wouldn't work to push the film backwards through the gate.[I just realized that I don't know how auto-reverse audio cassette players work - have to look it up.]

Also, reversing might have caused secondary problems in recording the master. The sensitivity of the master film to the electron beam changed during the recording due to outgassing of the moisture in the film, so the exposure had to be changed gradually during the recording. CBS never got this totally under control. It was one factor that caused poor yields of good films. Doing this forward and reverse could be a further issue.

[DVtyro]

Originally Posted by old_tv_nut

"Then the picture was be scanned by an electronic beam again" - in the player it was scanned by a light beam from a small "flying spot" CRT. I think maybe you understood this but typed the wrong thing?

Um... Er... I need to read up on how flying spot scanner works

Originally Posted by old_tv_nut

I just realized that I don't know how auto-reverse audio cassette players work - have to look it up.

It has two capstans and two pinch rollers (not mentioning Nakamichi system here).

[Electronic M]

Originally Posted by DVtyro

Um... Er... I need to read up on how flying spot scanner works

It has two capstans and two pinch rollers (not mentioning Nakamichi system here).

I would imagine that if tape...er um film tension could be maintained via the reels that it could work fine with a single capstan system for autoreverse...I own a TEAC X-3R and it's later identical cousin the X-300R that are 3 motor single capstan auto reverse stereo RTR tape decks... Most other RTRs especially ones that could record in both directions (the Teac only recorded in one direction because it only 3 had heads and erase would be on the wrong side of the record head in reverse) had 2 capstans as did most autoreverse cassette decks, but there's probably a single capstan auto reverse cassette deck out there too.

I don't know if there's any good videos of the B&K 1077 analyst out there but it too is a flying spot scanner....In a nutshell a magnetically deflected camera tube is always going to be significantly more complex and expensive than a CRT. A high speed light sensor that only measures the light of one fixed point is always going to be cheaper than a camera even if it needs a CRT display tube to be paired with it to do the scanning for it*....Which is exactly what a flying spot scanner CRT does. In a flying spot film scanner the film frame is placed over a CRT with short persistence phosphor (essentially only the point on screen that the beam of the gun is on at that instant is lit) set up to create a blank white raster...The CRT light projects through the film and since the only light at any given instant is from the specific spot on the film over the light from the CRT screen at the point the beam is at at that instant the light that passes through the film is exactly what the base band video signal looks like minus the sync (which would be added later) and a simple cheap single point photoelectric device can convert the light to electronic video.

*Heck in the late 60s Sylvania came out with the slide theater console it was a 23" color TV packaged with a full color flying spot slide scanner. It used a hidden smaller white phosphor CRT that projected through the film onto dichloric mirrors that split the light into separate R, G, and B primary color paths that each had a photoelectric device (photo multiplier tube IIRC) to convert them to electrical signals that were passed the main (color) CRT the viewer would watch.