TM 11-6720-242-35
(2) The camera is capable of operating in two
ating in the pulse mode and the POWRER switch is set
modes, autocycle and pulse. In the autocycle mode, the
to ON. Shutter speeds from 1/,100 to 1/8500 per
camera operates at various cycling rates over one cycle
second are a function of the velocity of film advance
per second. When the V/H ratio drops below one cycle
and the width of the exposure slit.
per second the crossover network automatically
e. E V/H Ratio Range. The cycling rate for a
switches the camera to the pulse mode through the
camera mounted in the forward-oblique position is
mode relay. In the pulse mode, the proper pulse rate is
scaled by a factor of 3.5:1. relative to the vertical
generated by the Intervalometer network which
cycling rate for a given E V/H signal. The factor is
automatically cycles the camera at the fractional rates
derived from the 20-percent angle of the principal ray
corresponding to the V/'H signal. This is accomplished
and format overlap of 60 percent. The total E V,'H
by adding a fixed signal (2 cps rate) to the scan drive
range is 0.04 to 1..5 knots per foot. Operation in the
amplifier and controlling the pulse rate to the scan
autocycle mode is from 0.177 to 1.5 knots per foot. For
control relay. The Intervalometer pulse, through the
a 60-percent overlap below an E V/H range of 0.177
relay driver, energizes the coil of the scan control relay
knots per foot, the camera automatically switches to the
to start the picture scan and the puck switch deenergize
pulse mode.
the coil through the relay driver to complete the picture
f. Resolving Power. Line weighted average
scan. Every time an exposure is made, the puck switch
resolution (LWAPR) is not less than 45 lines per
is close: and a ground signal is momentarily applied to
millimeter when tested with Aerecon Plus X film and
the scan control relay and the puck switch driver
using a standard Air Force contrast test target in
network.
In turn the driver network operates the
accordance with MIIL-STD-150. Resolution (dynamic) is
FRAMES REMAINING and OPERATE indicators and
22 lines per millimeter on axis coverage throughout the
provides the annotation signal to the pulse transformer
format and with a cycling rate of 2 cycles per second at
network. The transformer network provides the high/low
a 1/2000th second exposure.
pulse to the external airborne data annotation system.
g. Block Diagram Discussion.
The EXTRA PICTURE switch will cause the camera to
(1) As shown on the overall block diagram
expose a single frame during the pulse mode by
applying an independent pulse to the relay driver each
motor, feedback tachometer with network, amplifiers,
time the switch is depressed.
scan control relay and a gear train which drives the body
(3) Image
motion
compensation
(imc)
is
and magazine mechanisms (fig. 2-6). The purpose of
incorporated into the camera so that the lens is moved
the scan drive is to operate the drive mechanism in
along the line of flight during exposure. IMC is used
order to photograph at continuously variable rates from
only in the vertical position and only in the autocycle
one picture per second to eight and one-half pictures per
mode. Switching through the CAMERA SEL switch,
second. The cycling rate is controlled by a V/H input
mode relay, and operate relay provides the required
signal which is selected by the V/H SEI, switch sealed
signal to the solenoid driver which energizes the TIMC
by the CAMIERA SEL switch through the V/H inhibiting
clutch solenoid thus causing the time mechanism to
and scaling amplifier and controlled by the mode and
function.
operate relays before being applied to the scan drive
(4) The automatic exposure control (aec) assures
amplifier. This command signal controls the output of
that a constant level of exposure is maintained over a.
the scan drive amplifier and thereby the speed of the
broad range of picture taking conditions. The variables
scan motor. The command signal is compared to the
affecting exposure are terrain brightness, camera
tachometer signal to determine whether acceleration or
cycling rate, and film speed (aei). The camera controls
deceleration of the scan motor is required.
If
the level of exposure by varying the width of the slit,
deceleration is required the dynamic braking circuit
through which the object is photographed, and by
closes the loop causing the braking current to flow
controlling the opening of the diaphragm. Thus the slit
through the armature of the scan motor until the
width and the diaphragm opening are combined to
required speed of the system is attained. The output of
produce a total effective opening.
The feedback
the scan drive amplifier passes through the scan control
potentiometer, coupled to the aec mechanism, is driven
relay, which is controlled by the operate relay through a
proportionately to this effective opening. A voltage
relay driver, thence through the servo amplifier, the
proportional to the
output power drive and to the scan motor.
2-2
