Nikon D780 - Lock Mirror up for Cleaning

674
Menu Guide >
B
The Setup Menu
Use [Lock mirror up for cleaning] to lock the mirror up so that
dust that cannot be removed using the “clean image sensor”
option can be removed manually. Note, however, that because
the low-pass filter is extremely delicate and easily damaged, we
recommend that manual cleaning be performed only by a
Nikon-authorized service representative. For information on
cleaning the low-pass filter, see “Manual Cleaning” (
0
827).
Lock Mirror Up for Cleaning
G
button
U B
setup menu