Canon AT 1 - Manual (Page 83)

Using the Self-Timer
Obvious uses for the self-timer are self-
portraits and the inclusion of the photo­
grapher in a souvenir picture. The self-timer
can also be used in place of a cable release
to release the shutter gently and smoothly in
close range work like photomicrography or
copying.
Push the electronic self-timer lever
forward, then press the shutter button, and
the shutter will be released 10 seconds later.
While the self-timer is in operation, the self-
timer lamp flashes on and off. After you
finish taking a picture, the self-timer lever
should be reset to its original position. Other­
wise, it will function again the next time you
press the shutter button.