To illustrate what happens when someone tries to unsuccessfully outsmart the AF:
I was taking a picture of an Echinacea flower when a hummingbird moth (2nd sighting in my life!) flew by and hovered in front of another flower for short time:
View attachment 210549
By the time I realized I had the AF set to a single point in the centre instead of a zone, the moth was gone. I'm now resizing zones instead of switching to single point on my R8
(And I have the AF-ON button set to spot AF, I should have used that for the flower)