Canon EOS 3 User Manual (en)

AF Mode Selection
AF Modes
Different AF modes have different AF operation characteristics. The
camera has two AF modes: One-Shot AF for still subjects, and AI Servo
AF for moving subjects. (AI is an abbreviation for Artificial Intelligence.)
Select the AF mode which suits the subject.
One-Shot AF for Still
Pressing the shutter button halfway
activates AF operation and achieves
• The focusing point which achieves focus
flashes briefly and the in-focus indicator (
●) in
the viewfinder lights at the same time.
• When the <
> switch is set to <
>, the
beeper also sounds when focus is achieved.
• With evaluative metering, the exposure setting
(shutter speed and aperture) will be set when
focus is achieved. The exposure setting and
focus will be locked as long as the shutter
button is pressed halfway. You can then
recompose the shot while retaining the
exposure setting and point of focus.  See page
In-focus indicator
Focusing point 
If focus cannot be achieved, the in-focus indicator in the viewfinder will blink. If this
occurs, a picture cannot be taken even if the shutter button is pressed completely.
Reframe the shot and focus again. Also see “Manual Focusing” on page 52.
 04. C836-E (33~)  28-01-2003  11:10  Pagina 35