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Film Transport Mechanisms in Cameras (Movements) - what are the various types?


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Sorry for the lengthy topic wording. I didn't want to call it "Camera Movements" as that would be mistaken for something else. I'm sure this has all been covered in the forum previously, but perhaps not under one topic thread (I searched).

From what I have learned over the years, there are four basic types of camera movements (film transport mechanisms) in professional cameras with many variations:

1. pull-down claw - usually driven by a cam, variations include the Bolex' "trailing claw" and the Auricon's claw with bearings in the gate which have a stabilizing function. 

2. claw with pins mechanically linked - does this have a better name? I'm thinking of the "Mitchell-type" mechanically linked pull-down claw with registration pins. In the J.M. Wall camera this was designed to all fit in a compact module that could be taken out of the camera easily, the Arri BL had a similar design. The Arri-S and Milliken come to mind as other variations with a mechanically linked registration pin. 

3. fixed pin shuttle - used in the Bell & Howell 2709 and animation cameras, also used in optical printers

4. prism & drum - specifically for highspeed cameras

- please correct me/mansplain-away!

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The German Wikipedia lists four classes 0, 1, 2, and 3. Class 0 comprises everything where the film runs continuously in coordination with an optical compensation, class 1 collects simple advancement movements, class 2 those with additional means for locating the stock such as moving register pins, and class 3 is for fixed pilot pins. Basically equal, only projector mechanisms fit in, too.

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  • 3 months later...

it would be a terrible shame if someone didn't mention the famous "burp loop" used in some IMAX projectors.

Not a camera movement, but a strategy to move the large IMAX frames through the projector day after day with good registration while not destroying the perfs with a camera-like movement.

The film moves on continuous sprockets through a gate that has fixed pins. The movement is timed so that a 15 perf loop of film builds up on one side of the gate, and at the right moment a puff of air picks up the film off the register pins and the energy built up in the springy loop snaps the film 15 frames forward, where it drops back onto the pins one frame further advanced.

Kinda like an the shuttle movement in an old Acme optical printer, but with air instead of the lifting shuttle.

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