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Drum Camera
Millisecond Cinematography L.C. has developed a camera system capable
of shooting full format 35mm film from 120 to 12,000 frames per second
with excellent resolution and image quality. Instead of moving film from
a supply reel to a take-up reel, it spins a loop of unexposed film around
continuously inside the camera in a circle. The operator must load a 7
1/2 foot strip of film into the camera in order to take a picture. The
film goes into the inside track of a flywheel, or drum, which then spins
up to a constant speed. The camera waits with the unexposed film spinning
(at speeds up to 500 mph) shooting begins.
The operator of the drum camera must open the shutter, flash the lights
and fire the event, all within one revolution of the drum, to avoid double-exposing
the film. Automatic triggers must be set up when shooting above a few
hundred frames per second, so that all this happens at the right time.
The camera comes with sophisticated timing equipment to make the process
easy.
Shots are limited to 120 frames or five seconds of screen time, because
the camera only shoots one loop of film at a time. However, the timing
equipment used to synchronize fast events is very accurate; while there
are only get 120 frames per shot, it is possible to determine exactly
what will be on those frames. It also means that you do not waste any
film during camera run up or run down.
Floodlight illumination can be used up to about 1,200 frames per second.
Above this speed, shots must be illuminated with Milliseconds specialized
flash lamps, for two reasons. First, the amount of light needed at high
framing rates is very large. The exposure time of each individual frame
at top speed is around 1/50,000 of a second. These flashlamps are capable
of producing light which is 1,000 times brighter than sunlight. Second,
at the higher speeds, the shutter does not open and close fast enough
to limit the total exposure to within one revolution of the drum. The
flash unit will turn on and off precisely, creating a very bright light
pulse of the right duration.
High speed pin registered cameras currently available are capable of shooting
at up to 360 frames per second. The only choice to go faster than this
has been a prism camera, which moves film continuously behind a rotating
glass block, or prism. These cameras can shoot up to 2,500 frames per
second, but they require compromises in image quality and frame stability,
are difficult to control and waste tremendous amounts of film. The Millisecond
camera can shoot five times faster than a prism camera, with much better
results and no film waste.
Drum cameras have been used for over 30 years in scientific research to
photograph high speed events. The scientific research market routinely
photographs expensive experiments, and their requirements for reliability
and ease of use are extremely high. Much effort has gone into the design
of drum camera equipment over the years to meet these needs. The Millisecond
system incorporates this technology, and while being reliable and easy
to use, it does require a qualified operator to go out with it.
The Millisecond camera comes from the sole manufacturer of drum cameras
worldwide, Cordin Co. of Salt Lake City, UT. Cordin cameras have been
designed primarily for the scientific research market, and therefore have
had peculiarities which made them incompatible with the cinematography
market. The Millisecond camera was designed and built specifically to
meet the needs of the cinematography market, and the introduction of this
service marks the first time this technology is available to professional
directors of photography.
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