Canon POWERSHOT D20 User Manual page 5

Shooting Range and Focusing
Change the AF (auto focus) frame mode to suit the shooting conditions as
follows.
Press the
MENU
button, choose [AF Frame]
on the _ tab, and then choose the desired
option (p. 42).
_ Face AiAF
Detects people's faces, and then sets the focus, exposure (evaluative
metering only), and white balance (_ only).
After you aim the camera at the subject, a white frame is displayed around
the person's face determined by the camera to be the main subject, and up
to two gray frames are displayed around other detected faces.
When the camera detects movement, frames will follow moving subjects,
within a certain range.
After you press the shutter button halfway, up to nine green frames are
displayed around faces in focus.
_g_ If faces are not detected, or when only gray frames are displayed
(without a white frame), up to nine green frames are displayed in the
areas in focus when you press the shutter button halfway.
If faces are not detected when Servo AF (p. 115) is set to [On], the AF
frame is displayed in the center of the screen when you press the
shutter button halfway.
Examples of faces that cannot be detected:
Subjects that are distant or extremely close
Subjects that are dark or light
Faces in profile, at an angle, or partly hidden
The camera may misinterpret non-human subjects as faces.
No AF frames are displayed if the camera cannot focus when you
press the shutter button halfway.
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