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

Re: Coments re: Film Reg.




In a message dated 08/02/1997 21:12:10, you wrote:

<<I'd like to mention that using a sprocket which
intermittently starts and stops to pull down 24 fps film is standard practice
for theatrical projection, and has been for at least 80 years.>>

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.

Steven Gladstone

+++ thanks to Donna Chapman and Pacific Radio for support of the TIG in 1997
---
mailinglist digest available......posting guidelines on the webpage
the Telecine Internet Group  <http://www.alegria.com/telecinehome.html>


Follow-Ups: