Canon EOS A2 Instructions Manual page 23

Manual Focusing
1) Set the lens' focus mode switch to M.
* AIlAF mode indicators in the LCD panel
go out.
2) Turn the lens' manual focusing ring until
the subject appears sharp.
* The in-focus indicator lights to indicate
that the subject is in focus.
After autofocusing is completed in One-
shot AF mode when using a USM lens
equipped with a distance scale window,
the lens can be manually focused directly
without switching the lens' focus mode
switch.
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