Canon EOS 5D Mark III Instruction Manual page 213

You cannot take a picture during autofocusing. Take the picture while the
Live View image is displayed.
3
Select the AF point.
The AF point selection will change in

the direction you tilt the <9>. If you
press <9> straight down, the center
AF point (or center Zone) will be
selected.
You can also use the <6> and <5>

dials to select the AF point. The <6>
dial selects an AF point in the horizontal
direction, and the <5> dial selects an
AF point in the vertical direction.
4
Focus the subject.
Aim the AF point over the subject and

press the shutter button halfway.
 The Live View image will turn off, the
reflex mirror will go back down, and
AF will be executed. (No picture is
taken.)

When focus is achieved, the beeper
will sound and the Live View image
will reappear.
 The AF point used to focus will light
up in green.
 If focus is not achieved, the AF point
will blink in orange.
5
Take the picture.
Check the focus and exposure, then

press the shutter button completely to
take the picture (p.198).
Using AF to Focus
213