Canon EOS 90D Advanced User's Manual page 133

Meaning of Lit or Blinking AF Points
Pressing the < S > or < G > button lights up the AF points that are cross-
type AF points for high-precision autofocusing. The blinking AF points are
horizontal-line or vertical-line sensitive. For details, see "Supplemental
Information".
Setting the Initial AI Servo AF Position
When [ 8 C.Fn II-11: Initial Servo AF pt,
/ c ] ( = 566), you can manually set the initial position for AI Servo
for
AF.
1
Set the AF area selection mode to [H Auto selection AF]
(=131).
2
Set AF operation to [AI Servo AF] (=124).
3
Set the AF point (=132).
Selecting the AF Area and AF Point (Viewfi nder Shooting)
/ c ] is [1:Initial AF pt set
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