Canon EOS M6 Mark II Advanced User's Manual page 154

Metering Mode
By default, the camera will set the exposure as follows.
z
With [ q ], holding down the shutter button halfway will lock the exposure
setting (AE lock) after focus is achieved with One-Shot AF. In the [ w ], [ r ],
and [ e ] modes, the exposure is set at the moment the picture is taken.
(Pressing the shutter button halfway does not lock the exposure.)
With [ 8 : C.Fn I-7: AE lock meter. mode after focus], you can set whether
z
or not to lock the exposure (AE lock) when focus is achieved with One-Shot AF
( = 533).
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