Nikon D300 User Manual page 134

3
Frame a photograph, focus, and shoot.
Z
A
Non-CPU Lenses
If the maximum aperture of the lens has been
specified using the [Non-CPU lens data] item in
setup menu (pg. 197) when a non-CPU lens is
attached, the current f-number will be displayed
in the viewfinder and control panel, rounded to
the nearest full stop. Otherwise the aperture
displays will show only the number of stops (F,
with maximum aperture displayed as FA) and the f-number must be read
from the lens aperture ring.
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