Canon A-1 - Manual (Page 21)

The battery check button also serves to
cancel the self-timer or to cancel the shutter
in long exposures. The circuit is cancelled
the moment you press the button, and the
second shutter curtain will close when your
finger is removed from the button. The
shutter will not be released if you press the
shutter button while pressing the battery
check button.
–21–
Getting a Feel for Your A-1
Now that the battery is loaded, your
A-1 will function. Before loading the
film or doing anything else, play with
it a little. Operate the shutter button.
and the film advance lever until they
feel like natural extensions of your
fingers.
Shoot and develop at least one roll of
film with a new camera before using it
on a shooting expedition or on a trip to
make sure you know how to operate it
properly.
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