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Cheap Sync


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#1 Paul Bruening

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Posted 15 November 2009 - 11:08 PM

I've been thinking about ways to solve sync issues without spending wads to do it. My latest idea is to take a fundamentally unsyncable cam like an Eyemo. Glue a short strip of mag tape to the shutter blade (use something that can be removed with a solvent). Make sure the strip has a tone on it before gluing. Glue it right at the edge of the blade that opens to reveal the frame (remember to counter balance the opposite side). Mount a sound head inside the housing to read the strip. Use an old 9V battery powered microcassette for both the battery housing and mag head. Run the signal back to the main recording device. If you've got a stereo unit, run the bleeps to one channel and the normal mic sound to the other. Then back in post you only have to line up the head slate and match the frames to the bleeps. You could even pull ramps or have a wonky recorder and still line it all up.
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#2 Hal Smith

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Posted 15 November 2009 - 11:57 PM

I've been thinking about ways to solve sync issues without spending wads to do it. ............


Create the tape with a length equal to the circumference of the shutter and with exactly sixty cycles of sine wave so at 24fps you've got 60Hz playing back and you could record the microcassette's playback on the pilot-tone track of a Nagra and post produce the sound old school. Aha! A FrankenNagra to go with your FrankenMitchell! :D
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#3 John Sprung

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Posted 16 November 2009 - 12:41 AM

Probably easier than that, leave the camera in one piece, and attach a little AC generator to the motor, geared to give you 60 Hz at 24 fps or 50 Hz at 25 fps. That's how we did sync in my early days, before crystal. You can probably still find such motors for the Arri's. Or, you could put a light chopper disc on the motor shaft. Both would be easier than messing with mag film and the shutter. Getting the mag head close enough without hitting would be a royal pain.





-- J.S.
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#4 Hal Smith

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Posted 16 November 2009 - 10:03 AM

Rather than use recording tape on the shutter it might work to glue 60 small pieces of flexible plastic magnet material around the periphery of the shutter and use a tape head to sense the rotating magnetic field. That would eliminate the problem John mentioned since the head wouldn't have to be in mechanical contact with the shutter but could be spaced back a millimeter or so.

I'd try using a methacrylic resin two part adhesive. My experience is that the methacrylics are better at adhering to different surfaces than epoxies and cyanoacrylics (superglues). The consumer version methacrylics are usually labelled for plastic repairs, I find them in hardware store adhesive departments
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#5 Paul Bruening

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Posted 16 November 2009 - 01:02 PM

Thanks fellas. I've spent decades rejecting Eyemos because of their sync limitations. Assuming everything goes to computer anyway, crude sync tricks like slate bloops and timing bleeps actually become usable again.
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#6 Hal Smith

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Posted 16 November 2009 - 04:36 PM

Thanks fellas. I've spent decades rejecting Eyemos because of their sync limitations. Assuming everything goes to computer anyway, crude sync tricks like slate bloops and timing bleeps actually become usable again.

Don't forget head and tail slates. That way you can use a sound editing program to easily stretch or compress the length of the sound segment to match the picture's length.
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