Focusing Ring - Canon EF300mm F2.8L IS USM Instructions Manual

AF Stop Button
The AF stop function cannot be used with the
EOS EF-M on manual focus cameras.
On the EOS 630/600, EOS RT, EOS A2/A2E/5
or EOS10S/10, if the AF mode is set to AI
SERVO AF and film winding is set for
continuous shooting, autofocusing will not
resume when you release the AF stop button. To
resume autofocusing, release the shutter button
and then press it halfway down again.
When sport mode is selected on the
EOS A2/A2E/5 or EOS10S/10, autofocus will not
work when the AF stop button is released.
Release the shutter button and press it halfway
down again to resume autofocus.

5. Focusing Ring

The focusing ring always works, regardless of
the focus mode.
After autofocusing in ONE SHOT AF mode, focus
manually by pressing the shutter button halfway and
turning the focusing ring. (Full-time manual focusing)
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