Canon EOS 20D Service Manual page 27

General Information
7. Autofocus
7-1 Type:
7-2 AF points:
7-3 Focusing modes:
TTL-CT-SIR CMOS sensor (TTL Cross Type
secondary image Registration)
9
• Center AF point sensitive to f/2.8, focuses
on two vertical lines.
1) Autofocus
In the Creative Zone modes, the following
three modes can be selected:
[One-Shot AF]
When focus is achieved, the AF operation
stops and locks (AF lock).
(1) AF-priority (The shutter can be released
only when focus is achieved.)
(2) During evaluative metering, AE lock is set
when focus is achieved.
(3) In metering modes other than evaluative
metering, exposure metering continues in
real-time until the shutter is released.
(4) With applicable USM lenses, electronic ring
manual focusing can be used after focus is
achieved with One-Shot AF or if focus
cannot be achieved with One-Shot AF.
(5) Automatically set in the Portrait,
Landscape, Close-up, and Night Portrait
modes.
[Predictive AI Servo AF]
Tracks subject movement and focuses
continuously until the start of exposure.
(1) First shot during halfway pressing (SW-1):
• Creative Zone modes: Shutter-release
priority (shutter releases after the lens
drive stops during focusing).
• Sports, Full Auto, No Flash modes (AI
Servo AF): AF priority
(2) 2nd shot onward during continuous
shooting: Shutter releases after the lens
drive stops during subject tracking.
(3) Automatically set in the Sports mode.
(4) Sports mode: Beeper provided, no focus
confirmation indicator
(5) Creative Zone modes: No beeper, no focus
confirmation indicator
(6) If focusing is impossible, the focus
confirmation icon blinks.
(7) With applicable USM lenses, electronic ring
manual focusing can be used if focus
cannot be achieved.
22