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Re: Sony HD Telecine Review

<< True . . . but print film has Eastman Kodak rectangular perforations
 which are optimised in shape for repeated runs without wear and tear.
 Camera negative stock has Bell & Howell perforations (barrel-shaped)
 which are designed for precise fitting to register pins. >>

I believe the perfs on Estar print film were changed just a couple of years
ago to make film tears less likely than with the old B&H print perf.  It's a
subtle change that affected only the radius of the corners, and was
implemented due to the "stiffness" of the Estar base, which is different than
Acetate or Nitrate base.  Needless to say, it was a contingency Mssrs. Bell
and Howell could not have forseen when they devised their first film
perforator in 1907!

But the fact remains: by design, print film **is** quite a bit more robust
than negative!

While registration in a camera is controlled by a pin that fits the perfs,
this is not the case in ordinary film projection.  The sprocket teeth or
pulldown claw tips are actually about 40% smaller than the perfs, to allow
for shrunken film, imperfect splices, and the like.  Side-to-side steadiness
(a.k.a. weave) is controlled by guides in the film channel on the aperture
plate, and top-to-bottom steadiness (a.k.a. jitter) is controlled to a large
extent by the pressure of the film shoe on the edges of the film.  I have to
wonder if perhaps the Sony machine's fancy electronic registration system
wasn't necessistated by the fact that it apparently has no aperture plate or
film shoe in the usual sense.  If that is so, it would be interesting to see
what happens with warped or fluted film!  I did not get to see the most
recent demonstrations at ITS, so if anybody out there can shed some light ...

Christopher Bacon

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