Setting The Exposure Counter; Viewing And Focusing - Polaroid Land SX-70 User Manual

Gears in the front cover must engage the main
gear train of the camera before the gear train
is put into motion. A switch (S7) located in the
forward section of the gear train compartment
initiates the application of power to the gear
train drive motor. Switch (S7) is actuated by two
components
(1) A projection on the front cover latch
(Figure 1-6 A), and
(2) A post on the right rear edge of the front
cover (Figure 1-6 B).
Figure 1-6 S7 contacts open and closed
Thus, the cover must be fulled closed, the gears
engaged, and the latch fully seated, in order to
actuate the drive motor.
As S7 closes, power is applied to the drive motor
(S8 is also involved and is discussed in a following
paragraph), the gear train is set in motion and
actuates a device called the film pick. The pick
engages the dark slide, pushes it into the spread
rolls and the dark slide is ejected from the lower
front edge of the front cover. The camera is now
ready to take the first picture.

4. Setting the exposure counter

When a used film pack is removed from the film
chamber, the action automatically resets the
exposure counter at the rear of the camera to the
start position, closing S8. With a new film pack
installed and the front cover closed and latched (
S7 closed), the motor is powered, and the dark
slide is ejected. The exposure counter turns
to number 10 (Figure 1-7), indicating that 10
pictures remain in the pack.
Figure 1-7 Counter

5. Viewing and focusing

Viewing and focusing is accomplished through
a reflect system (Figure 1-8 A). In the viewing
mode the image passes through the lens to a
fixed mirror which reflects it down to the Fresnel
viewing screen. The viewing path from the
viewfinder eyepiece lens is from a parabolic
mirror and wafer lens, off the fixed mirror to the
Fresnel screen. On most cameras the Fresnel
screen contains a circular split-image aera which
is used to focusing aid. A knurled knob (the
focusing wheel) on the shutter housing is rotated
to adjust the camera focus. The scene is in focus
when a vertical line within the split-image aera
is perfectly straight. On early cameras (without
a split-image feature), the scene is in focus
when the image seen on the Fresnel screen is
sharpest.
6. Viewing and focusing
The exposure is made by pressing the release
button. This completes the electrical circuit to the