Nikon D780 DSLR Camera (Body Only) - Manual (Page 216)

170 Shooting Settings
Long Time-Exposures (M Mode Only)
The camera offers two options for long time-exposures: Bulb
and Time. Long time-exposures can be used for pictures of
fireworks, night scenery, the stars, or moving lights.
• To prevent blur, use a tripod or an optional wireless remote
controller or remote cord.
Shutter speed: Bulb (35-second exposure)
Aperture: f/25
Shutter
speed
Description
Bulb
The shutter remains open while the shutter-release button
is held down.
Time
The exposure starts when the shutter-release button is
pressed and ends when the button is pressed a second
time.