[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Coments re: Film Reg.



With apologies to those who thought this was the telecine internet group ...

<< At least this is how my movie cameras, and my Regular 8mm, Super 8mm , and
16mm Projectors work. >>

What you are describing is the pulldown claw type of mechanism which was
almost universally used on smaller format cameras and projectors.  Something
akin to it is also used in pin-registered cameras and optical step printers
-- and presumably the earlier prototypes of the Sony HD telecine.

Geneva motion (and similar) machines that use a sprocket that turns
intermittently to pull the film down are typically 35mm and larger.  Hence
they are primarily used for theaters, not home movies.  A few 16mm projectors
were made this way, but they are few and far between.  Aside from the
superior film handling of a sprocket which engages multiple perf holes at all
times (claw pulldowns must let go of the film briefly so the claw can return
to the top of its travel), 35mm sprockets engage the perfs on both sides of
the film -- something that would be cumbersome to do with a claw.  I would
expect that these are the same reasons Sony has apparently elected to go with
this type of drive on the most recent version of their HD machine.

<< Thanks for saving me alot of writing.  I myself was wondering whether he
thought the film frame was pushed, or pulled into place in the gate by a
sprocketed roller ("for at least 80 years").

Mike >>

Just in case you wanted a serious answer, the film is brought to the upper
loop just above the aperture plate from the supply reel by a continuous feed
sprocket.  The intermittent motion sprocket is below the gate and pulls the
film through.   These machines are not meant to run backwards!  Depending on
the design of the projector, the film makes a lower loop of specific
dimension (to keep the sound in sync), passes over another continuous feed
sprocket, and then goes on to the damper rollers in the sound head.   

Christopher Bacon


---
mailinglist digest available
TIG subscriber count is 840 on Fri Aug  8 10:50:43 PDT 1997
the Telecine Internet Group  <http://www.alegria.com/telecinehome.html>