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Importance Of Variable Shutter
Adjustable shutter gives cinematographer still-camera flexibility in exposure control to “stop” fast action or to maintain exposure levels under variable light conditions
By JOHN FORBES
ONLY WITH A VARIABLE shutter is it possible to shoot fast action moving across the camera field and get a crisp, blurr-less image, as in (he picture below.
There are few fields of professional motion picture pho¬ tography that do not require, at some time or other, the ad¬ vantages of the variable shutter. There are two principal :
uses for the variable shutter: (1) to make fades or lap-dis ]
solves in the camera, and (2) to alter the exposure time '
interval.
The conventional motion picture camera shutter of this ;
type is a two or three-segment disc, the segments of which can be adjusted to alter the size of the shutter opening. As ■
in still photography, the “faster” the shutter speed the bet e
ter the camera is able to “stop” fast action without the [
blurring that would result in the image where a slower i
shutter speed is used. j
Except for the Kodak 16mm Cine-Special, until recently |
the variable shutter was found only in professional 35mm i
motion picture cameras such as the Mitchell. Today, the importance of the variable shutter in both professional and non-professional cinematography has been fully recognized ;
and we now find an increasing number of 16mm cameras offering this feature. Nor has the 8mm movie maker been neglected. Bolex, in its Model B-8VS cine camera, features a variable disc shutter that enables this camera to do any i
thing its 16mm contemporaries can do with this feature. |
To describe briefly tbe functions of the motion picture camera shutter, when we expose a frame of film, the film is held motionless in the gate of the camera for a fraction of a second. Before the next frame can be exposed, the film i
must be advanced in the gate in order to bring an unex ;
posed frame in place for the next exposure. During this |
"STOPPING" HORSE in mid-air was simply a matter of closing down the shutter opening for a "faster” shutter speed and opening up the lens diaphragm to equalize the exposure.
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AMERICAN CINEAAATOGRAPHER