Canon EOS 5D MARK III Instruction Manual page 23

._,2: Custom Controls
During metering, when you press the button assigned to this function,
the camera will switch to the AF point registered on page 324.
*3: In step 3 on page321,when you press the <INFO.>button,you can select [Switch
only when btn is held] or [Switch each time btn is pressed].
During metering, you can select an AF point directly with the <0> dial or
<,_ > without pressing the <[]> button. With the <O> dial, you can select a
left or right AF point. (With Zone AF, the selected zone will change in a loop.)
*4: If you use <._;_,> and pressthe <INFO.>buttonin step 3 on page321, you can press
<.;,;_,> straightdown to select [Switch to center AF point] or [Switch to registered
AF point].
When you press the shutter button halfway, only exposure metering is
performed.
When you press the button assigned to this function, you can lock the
exposure (AE lock) during the metering. Convenient when you want to
focus and meter the shot at different areas or when you want to take
multiple shots at the same exposure setting.
The exposure will be locked (AE lock) while you press the shutter
button.
When you press the button assigned to this function, you can lock the exposure
(AE lock). The AE lock will be maintained until you press the button again.
Convenient when you want to focus and meter the shot at different areas or
when you want to take multiple shots at the same exposure setting.
_L_if you aSsign [AE lock (While button pressed)] to the Shutter button, any
: buttons assigned to [AE lock] o[ [AE !0Ok (h0!d)] wil! a!s° work as [AE !0Ck
(while button pressed)],
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