Canon EOS M50 Mark II Advanced User's Manual page 90

Recomposing the Shot
Depending on the scene, positioning the subject toward the left or right to include a
balanced background will result in a picture with better perspective.
Pressing the shutter button halfway to focus on a still subject will lock the focus on that
subject. Recompose the shot while keeping the shutter button pressed halfway, and then
press the shutter button completely to take the picture. This is called "focus lock."
Note
The camera continues to focus on any faces initially detected and focused on, even
if you recompose the shot.
Shooting Moving Subjects
Pressing the shutter button halfway tracks moving subjects to keep them in focus.
Keep the subject on the screen as you hold down the shutter button halfway, and at the
decisive moment, press the shutter button completely.
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