Nikon Nikon 1 AW1 Reference Manual (en)

If the lens supports autofocus with manual override, you can
focus using autofocus and then keep the shutter-release but-
ton pressed halfway and rotate the lens focus ring to fine-
tune focus manually. 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 during movie
recording or in slow-motion movie
mode).  The display will be zoomed in
to the magnification selected in Step 1
and a navigation window will appear
in a gray frame at the bottom right of
the display.
Navigation window
Use the multi selector to scroll to areas
of the frame not visible in the display.
J to exit zoom.