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Re: Comments re: Film Reg.



>I thinnk that the difference here is that, the Sprocket wheels are always
>moving at a constant speed and the film is not. A CLAW is used to engage the
>film, at or near the aperture plate, and pull the film through one frame at
a
>time. Because the film starts and stops, there is a loop, above and below
the
>aperture plate (GATE), between the gate where the film is moving in an
>intermittent motion, and  the sprocket rollers which drive the film. At
least
>this is how my movie cameras, and my Regular 8mm, Super 8mm , and 16mm
>Projectors work.
>There are of course exceptions to this rule. At frame frates above 500 FPS
>(So I believe) intermitent motion becomes mechanically impossible, and so In
>that case the film is transported continuosly, with the image being
recorded,
>through a rotating prism. BTW. Flatbed Editors used this rotating prism
>method for film transport.
>So As I understand it, the sprocket rollers, drive the film at a continuous
>rate. The CLaw pulls the film through the Aperture area, of the camera or
>projector, with an intermitent rate. As to what drives the telecine I have
no
>idea, usually  60 herz in the U.S.

Well, actually, in professional projectors a Geneva movement (or "Maltese 
Cross", which drives a precision sprocket -- intermittently --  one frame 
at a time) is used for pulldown, not a claw.  Claw-type movements, with 
their cams, etc,  wear down -- projectors run many more hours than 
cameras do, with far less maintainance.  (Look at how lousy most 
projection is these days.  I sat through a film with poor registration 
the other night because the Geneva probably had run dry for a year or 
two!)  

Still, I don't see the logic in doing this in a telecine anymore -- does 
anyone really miss FR35s and TP66s?  (OK, the TP66 had claws, the FR35 
had a stepper pulldown, but I am talking about using an intermittent.)  
Looks to me like Rank and Philips had done pretty well just using 
continuous motion -- gentle on the neg, too.

But Sony is as Sony does, to paraphrase the worst film of a couple of 
years ago.

John Snopes
My first post here, I'm a newbie, a DP in Muncie, Indiana. 
Don't mean to insult multiplexes, the claw-user, or Robert Zemeckis.  
Sorry if I failed.



+++ thanks to Donna Chapman and Pacific Radio for support of the TIG in 1997
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