Here's how to check the mercury battery
for sufficient power. First set the Film Speed Scale to ASA 100 (use the
1.8 index) by lifting up and turning the ring around the Shutter Speed Dial.
Then turn the entire Shutter Speed Dial to a setting of 30 (1/30 second).
Turn the Lens Opening Control Ring to EE to turn the electric eye on.
2.
When all of these settings have been made, aim the camera (while looking
through the viewfinder) at the sky or some other bright object. The
battery has sufficient power if the Exposure Indicator swings up to or
over the number 16 on the scale. If it does not swing up to this point,
then the battery is weak and should be replaced.
NOTE: Always turn the Lens Opening Control Ring to OFF when
the camera is not being used to conserve the battery power.