Canon EOS 20D Instruction Manual

Page of 168
f Selecting the AF ModeN
66
* About Predictive AF
If the subject approaches or retreats from the camera at a constant rate, 
the camera tracks the subject and predicts the focusing distance 
immediately before the picture is taken. This is for obtaining correct 
focus at the moment of exposure.
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When the AF point selection is automatic, the camera first uses the 
center AF point to focus. During autofocusing, if the subject moves 
away from the center AF point, focus tracking continues as long as 
the subject is covered by another AF point.
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With a manually selected AF point, the selected AF point will focus 
track the subject.
AI Focus AF switches the AF mode from 
One-Shot AF to AI Servo AF 
automatically if the still subject starts 
moving.
After the subject is focused in the One-
Shot AF mode, if the subject starts 
moving, the camera will detect the 
movement and change the AF mode 
automatically to AI Servo AF. 
AI Focus AF for Automatic Switching of AF Mode
When focus is achieved in the AI Focus AF mode with the Servo mode 
active, the beeper will sound softly. The focus confirmation light <
o> in the 
viewfinder will not light.