Nikon 900 - Manual (Page 36)

- 36 - Basic Photography: Focus Settings
Focus Lock
If the color LCD monitor is on when the camera is set to
“Autofocus” or “Macro Close-Up,” focus will be continually
adjusted according to the distance to the subject (if the LCD
monitor is off, focus settings will be adjusted only when the
shutter button is pressed half-way). Pressing the shutter-release
button half-way “locks” focus at the current position. Focus will
remain unchanged as long as the shutter button is held in this
position, even if the distance to the subject should change. This
is known as “focus lock” and can be used to manually adjust
focal depth.
For example, in the following composition, the camera is fo-
cused on a distant point (shown by the
mark in the view-
finder), with the result that both distant and nearby objects are
in focus.
To create the same composition at a lower focal depth, so that
only objects in the foreground or middle distance are in focus,
focus the camera on a nearby object and then press the shutter
button half-way. Without removing your finger from the shut-
ter button, return the camera to its original position and then
press the shutter button the rest of the way down. Objects at
the original focus distance will remain in focus, but other objects
may not be in focus, depending on the relative distance to the
original focus point.