Nikon 1 J5 Reference Manual page 258

If AF-S or AF-C is selected for Focus mode and the lens sup-
ports autofocus with manual override, you can focus using
autofocus and then keep the shutter-release button pressed
halfway and rotate the lens focus ring to fine-tune focus man-
ually. To refocus using autofocus, press the shutter-release
button halfway again.
To zoom in on the display for more
precise focus, press J (note that this
feature is not available in some
modes). A navigation window will
appear in a gray frame at the bottom
right of the display.
Navigation window
Command dial
Use the command dial to zoom in or
out (to a maximum magnification of
10×) and the multi selector to scroll to
areas of the frame not visible in the
n
display. Press J to exit zoom.
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