Nikon D780 DSLR Camera (Body Only) - Manual (Page 158)

112 Shooting Settings
A Non-CPU Lenses
Use the lens aperture ring to adjust aperture. If the maximum aperture of
the lens has been specified using the [
Non-CPU lens data ] item in setup
menu 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 F 0 ) and the f-number must be
read from the lens aperture ring.
A Depth-of-Field Preview
Aperture can be stopped down by pressing
and holding the
Pv button. Depth of field (the
range of distances that appears to be in focus)
can then be previewed in the viewfinder.