Canon Powershot TX1 User Manual page 49

The AF frame appears as follows when the shutter button is
pressed halfway.
- Green:Shooting preparations complete
- Yellow:Focusing difficulty (Face Detect AF set to [Off])
The following occurs when [On] is selected.
- A maximum of 3 frames will be displayed at the positions
of faces the camera detects. At this point, the frame the
camera judges to be the main subject appears in white
while the others appear in gray. Pressing the shutter
button halfway displays up to 9 green AF frames.
- If no white frame displays and all the frames appear in
gray, or if a face is not detected, the focus will change as
follows according to the AF Mode setting (p. 45).
- When [Single] is set: Camera will automatically select
the AF frame from the 9 AF frames and focus.
- When [Continuous] is set: Focus using the AF frame in
the center.
- The camera may mistakenly identify non-human subjects
as a face. If this occurs, set Face Detect AF to [Off].
- In certain cases, faces may not be detected.
Examples:
- Faces near the screen edges or faces that appear
extremely small, large, dark or bright in relation to the
overall image.
- Faces turned to the side or at a diagonal, or faces with a
portion hidden.
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