PHASE LOCK SHUTTER SYNCHRONIZATION
Shutter Phase Lock is the term used to describe
these specialized Model 4BL & 4CL precision
35mm high speed motion picture cameras. These cameras
are equipped with electronic phase lock speed control
which allows you to synchronize the operation of
multiple recording cameras at various sites during
mission tracking.
The servo electronics synchronize the midpoint
of the camera shutter opening to the leading edge
of the external reference frequency (derived from
IRIG or other timing standard). In multiple camera
operations, the system is used to position each
camera's shutter, through an external pulse, to
a very precise point in time, allowing the cameras
to run in synchronization. In addition, by electrically
phase shifting the phase lock reference pulse at
multiple sites, it is possible to shift the shutters
by some known degree… i.e. 60, 90, 120, or 180.
With film from different camera stations time correlated,
data reduction is greatly simplified resulting in
considerable cost savings.
Phase locked cameras offer a unique method of verifying
phase lock accuracy with an edge of film mark. The
mark represents 20 of shutter opening derived from
a special shutter position sensor. The blank line
in the middle of the mark shows the incoming phase
lock reference frequency. This phase lock indicator
gives the viewer a clear indication that the camera
was phase locked within 5 of the incoming reference
frequency.
Other features of these cameras are the same as
the Models 4B and 4C. They are full format 35mm
using a precision rotary prism optical system for
image motion compensation on continuously moving
film. The prism operates synchronously with a disc
shutter to provide uniform exposure.
Models 4BL and 4CL consist of camera body, magazine,
automatic take-up/brake assembly, drive motor, power
amplifier and control unit.
The 4BL and 4CL are operationally identical. They
vary only in the configuration of the film magazine
mounting. The 4CL, like the 4C, is mounted at an
angle to accommodate the use of larger lenses or
telescopes.
Camera speeds in phase lock are 100 to 1000 frames
per second, indefinitely variable. In Cine mode,
speeds are 100 to 1000 frames per second in ten
frame per second increments.
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