Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 180)

Exposure Lock (AE Lock)
Effect of AE Lock
You can lock the exposure when you want to set the focus and exposure separately or when
you will take multiple shots at the same exposure setting. Press the <
> button to lock the
exposure, then recompose and take the picture. This is called AE lock. It is effective for
shooting backlit subjects, etc.
1.
Focus on the subject.
Press the shutter button halfway.
The exposure value will be displayed.
2.
Press the < > button ( ).
A [ ] icon is displayed in the lower left of the screen to indicate that
exposure is locked (AE lock).
Each time you press the < > button, the current exposure setting is
locked.
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