Optical sound camera questions

[Dirk DeJonghe]

I am installing a 16mm optical sound camera to make my own sound negatives. I am looking for a way to inject my audio coming from a WAV file into the camera while keeping in sync. In the old days a SEPMAG follower was used and the 48/50hz pulse out of the follower was used to drive the camera.

Is there anyone with a good memory who remembers most of the details. The camera is a Picot 50 from the mid 80s.

[Simon Wyss]

Correct, at first, the pilotone was used to control the SEPMAG machine, later the switching was reversed so that the tape speed was controlled after the signal because it is easier to monitor the tape recorder and not the magnetic film drive with its heavy flywheels.

I think you can go far with crystal control. Standard says maximum deviation of ± half a frame per 16,000 frames. Crystal control goes well with digital equipment, the CD works on a crystal-generated and downcounted signal. If you see a way of proofing the crystal control, accuracy might be still better like ± a quarter frame per 32,000 frames. I cannot tell you the exact way of doing it but a computer’s crystal frequency can be captured (before or after downcount, I don’t know the details) for a common reference.

 

Perfect synch is of course attained when both synchronous motors of picture and sound camera run on the same mains outlet.

[Dirk DeJonghe]

I really want to run a computer with Audacity on it and play the sound file in sync to the mains frequency. The optical camera runs on 3x220v, I don't see any other sync input so I suppose it is synced to the mains frequency.

I need to be able to transfer full 610 meter reels with less than one frame error. How will the computer sync to the mains frequency?

I used to transfer Nagra tapes, synced by SLO to the mains frequence, to SEPMAG also synced to mains. In this case the computer will take the place of the Nagra and the SEPOPT the place of the SEPMAG.

[Will Montgomery]

You may want to give Tommy Aschenbach a call or email. He's developed software for cine optical sound and does 16mm sounds prints all the time at his lab. They work with the National Archives near Washington, DC. He would be a good guy to bounce ideas off at the very least.

 

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