Focus Autofocus; Focus; With A Stationary Subject - Nikon N5005 AF Instruction Manual

FOCUS
AUTOFOCUS
In autofocus mode, the shutter cannot be released until the
subject is correctly focused, and once in focus, the focus is
locked as long as the shutter release button remains lightly
pressed.
If subject is moving, focus tracking works automatically. The
focus tracking system enables the camera to analyze the speed
of the moving subject according to focus detection data, and
drive the autofocus lens by anticipating the position at the exact
moment of exposure. So you can get correctly in-focus-pictures
for most moving subjects, as well as stationary subjects.
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With a stationary subject
When subject is in focus, autofocus stops and . appears.
Once subject is in focus, focus is locked. If subject moves, re-
move your finger from shutter release button, then lightly press
it again to start autofocus with focus tracking.