Canon AE-1 Instructions Manual page 38

Composition
Since the AE-1 has automatic exposure
control with shutter priority, you can con-
centrate
on
the actual picture you are
going
to
take without worrying about exposure differ-
ences that may occur with changing subjects.
Viewing is performed through the lens, and
there
is
no difference between the viewfinder
image and the image exposed on the film, a s
opposed to the image provided by a separate
viewfinder which is affected by the parallax
between the viewfinder and the camera lens.