David Busch's Nikon Z50 II Guide to Digital Photography

Mastering the Mysteries of Focus

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Modern digital cameras like the Z50 II can identify potential subject matter, lock in on human faces, animals, birds, vehicles, and airplanes, and automatically focus faster than the blink of an eye. Usually. Of course, sometimes a camera’s AF will zero in on the wrong subject, become confused by background pattern, or be totally unable to follow a fast-moving target like a bird in flight.

One key problem is that the camera doesn’t have any way of determining, for certain, what subject you want to be in sharp focus. It may select an object and lock in focus with lightning speed—even though the subject is not the one that’s the center of interest of your photograph. Or, the camera may lock focus too ...