Nikon D7200 body - Manual (Page 117)

93
Focus Lock
Focus lock can be used to change the composition after
focusing, making it possible to focus on a subject that will not be
in a focus point in the final composition. If the camera is unable
to focus using autofocus (
0 96), focus lock can also be used to
recompose the photograph after focusing on another object at
the same distance as your original subject. Focus lock is most
effective when an option other than auto-area AF is selected for
AF-area mode (
0 86).
1
Focus.
Position the subject in the selected focus point
and press the shutter-release button halfway to
initiate focus. Check that the in-focus indicator (
I)
appears in the viewfinder (viewfinder photography) or that
the focus point has turned green (live view).
Viewfinder photography Live view