Canon EOS R3 Advanced User's Manual page 415

Servo AF for Moving Subjects
This AF operation is suited for moving subjects. While you hold down the shutter button
halfway, the camera will keep focusing on the subject continuously.
When focus is achieved, the AF point will turn blue. The beeper will not sound even
when focus is achieved.
The exposure is set at the moment the picture is taken.
For details on the continuous shooting speed for continuous shooting, see
Drive Mode.
Caution
Accurate focusing may not be possible at high aperture values or depending on the
lens, the distance to the subject, and how fast the subject is moving.
Zooming during continuous shooting may throw off the focus. Zoom first, then
recompose and shoot.
Consider shooting with One-Shot AF if Servo AF operation is unsteady for still
subjects.
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