Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 231)

Caution
With (evaluative metering), holding down the shutter button halfway when
shooting with [ One-Shot AF ] locks the exposure value (AE lock). With (partial
metering), (spot metering), or (center-weighted average metering),
exposure is set at the moment the picture is taken (without locking the exposure
value when the shutter button is pressed halfway).
With [
: AE lock meter. mode after focus ] ( ), you can set whether or not to
lock the exposure (AE lock) once subjects are in focus with One-Shot AF.
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