Canon AE-1 - Manual (Page 42)

Operation for General Photography
The AE-1 is an Automatic Exposure
camera with a shutter speed priority system
which electronically controls the aperture
opening for the given shutter speed to ensure
the optimum exposure. Canon's shutter speed
priority system has been adopted by this
camera in the idea that a photograph is an
instant snatched from elapsing time.
The shutter speed priority system is ideal
for catching fast-moving subjects, especially at
the decisive moment.
Furthermore, the shutter speed priority
system allows you to control image blur at
will and to emphasize the movement of the
subject. For action or other such situations,
you can realize all photographic aspirations.
23