TM 11-6720-242-35
(2) With CAMERA SEL switch 3S4 set to FWD, the
roller. The pressure roller is actuated (via a gear and
V/H high input is connected to the top of the two scaling
belt train) by a capping cam that is rotated in
networks R10, R21, and R22 and R11 and R12. Each
synchronism with the prism (fig. 2-6). When the prism
network
reduces
the
V/H
voltage
to
has rotated through its 45-degree acceleration angle, the
0.4/volt/cycle/second while the input remains above a
pressure roller presses the film against the rotating puck
gradient of 30.36 volts/cycle/second for autocycle mode
and causes film advance until the 90-degree scanning
of operation.
angle of the prism is completed (fig. 2-14).
(3) With CAMERA SEL switch 3S4 set to VERT,
d. Shutter speed is a function of film travel and the
the V/H vert-1 voltage is connected to the junction of
variable width of the slit in the focal plate. Relative
resistors R10 and R21 of the network serving the
shutter speeds from 1/100 second to 1/'8000 second are
electronic mode switch and Intervalometer circuits (fig.
attainable with this arrangement.
e. Automatic exposure control (aec) varies the
the junction of resistors R11 and R12 of the network
width of the slit and the area of the aperture opening. A
serving the aec and scan circuits. The output of both
complete description of aec functioning is contained in
networks remains at a gradient of 0.4 volt/cycle/second
while the V/H input remains above a gradient of 8.929
f. Image motion compensation (imc) moves the
volts/cycle/second.
lens back and forth parallel with the slit. A complete
(4) Note that the resistor R2 becomes a part of the V/H
description of time functioning is contained in paragraph
vert-2 aec and scan scaling network when operate relay
2A4K1 is energized. When relay 2A4K1 is deenergized,
g. The adas components in the body include a lens and
resistor R2 is disconnected and R1 is substituted into
mirror assembly consisting of a 1 inch f,/2.0 lens, two
the network to enable EXTRA PICTURE switch iA3S5 to
mirrors, and the rha (fig. 2-13). The lens and mirror
initiate single picture taking with the OPERATE switch
arrangement projects the coded image to the film for
1A3S2 set to OFF but with POWER switch 3S1
photographic recording. A complete description of adas
remaining in the ON position (fig. 6-14). (5) A third
functioning is contained in paragraph 2-14.
voltage divider consisting of resistors R13, R14, R15,
2-7. Functioning of Automatic Exposure
and zener diode VR1 (fig. 2-1) receives a + 15 vdc
Control
input and supplies a fixed output of 0.8 volt/2
cycles/second for the aec and scan circuits while the
camera operates in the pulse mode.
Automatic exposure control (aec) adjusts both the width
b. AEC Amplifier Functioning (fig. 6-15).
of the exposure slit in the focal plate and the opening or
(1) The V/H signal voltage from the scaling network
closing of an aperture which is located between the front
is connected to the aec log amplifier AR1 on the aec
and back lens elements. A V,'II signal generated by
board assembly 2A5, through a bias network. An input
aircraft equipment and a photocell assembly, located
of +25 vdc is connected to the bias network through
close to the prism, are basic for aec operation. The V/'I
resistor R1 and potentiometers R13, R14, and R15,
signal is connected to the camera through the :IAN. or
which are connected in series with and regulated by
AUTO contacts of VI/H SEL switch 3S1 on the control
zener diodes VR2 and VR3 and resistors R16 and R17.
panel.
(2) In addition to the 15 vdc, the aec photocell
a. Scaling Networks (fig. 2-1).
amplifier AR2 receives an input from the aec photocell
(1) From V/H SEL switch 3S1, the V/H input
assembly 1A2, located in the body. The output of
signal voltage is channeled to two voltage dividers on
photocell 1A2 is applied to differential amplifier AR3
the control board assembly 2A4 and fed back to the
simultaneously with the output of photocell amplifier
aircraft equipment as an auxiliary data annotation
AR2.
system (adas) reference voltage. The channels are
(3) The photocell and its associated circuit act as a
designated V/H high, V/'H vert-1, and V,/H vert-2. Their
voltage divider network whose resistance varies
variable inputs are at a gradient of 8.929
inversely with light intensity. When a low light condition
volts/cycle/second for vertically mounted cameras and
exists, the network applies a large portion of the aec
30.36 volts./cycle /second for cameras mounted in a
output voltage to the chopper amplifier. As the light
forward oblique position.
intensity increases. The
2-6
