Canon EOS R3 Advanced User's Manual page 421

: Expand AF area:
Focuses using one AF point [
subjects, which are difficult to track with 1-point AF.
Focusing on your preferred subject is easier than with Flexible Zone AF.
When Servo AF is used, first you will focus using an AF point [
: Expand AF area: Around
Focuses using one AF point [
makes it easier to focus on moving subjects than with Expand AF area:
When Servo AF is used, first you will focus using an AF point [
] and the AF area outlined here in blue. Effective for moving
] and the surrounding AF area outlined here in blue, which
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