Nikon D300 - Manual (Page 344)

318
U
USB
Choose a USB option for connection to a computer or PictBridge
printer. Choose [MTP/PTP] (the default setting) when connecting
to a PictBridge printer or an optional WT-4 wireless transmitter or
when using Camera Control Pro 2 (available separately; see page
368). See page 225 for information on selecting a USB option for
use with Nikon Transfer.
Dust off Ref Photo
Acquire reference data for the Image Dust Off option in
Capture NX version 1.3.5 or later or Capture NX 2 version 2.1.0 or
later (available separately; for more information, see the software
manual).
[Dust off ref photo] is available only when a CPU lens is mounted
on the camera. A lens with a focal length of at least 50 mm is
recommended. When using a zoom lens, zoom all the way in.