Canon A-1 - Manual (Page 51)

ASA, press in the ASA film speed dial lock
button with your fingernail and turn the
outer knurled edge of the dial until the
desired film speed rating is aligned with
the film speed index. The dial cannot be
turned lower than ASA 6 or higher than
ASA 12800.
There is an exposure compensation scale on
the .-\SA film speed setting dial. The func­
tion of this scale will be explained later, but
at this point, please note that this scale
should be set at “1” for normal ,\E pho­
tography.
8-