Nikon D3000 Reference Manual page 91

4
Open the shutter.
Bulb: After focusing, press the shutter-release button all the way down. Keep
the shutter-release button pressed until the exposure is complete.
Time: Press the shutter-release button on the remote control all the way down.
The shutter will open immediately (quick-response remote) or two seconds
after the shutter-release button is pressed (delayed remote) and remain open
until the button is pressed a second time.
5
Close the shutter.
Bulb: Take your finger off the shutter-release button.
Time: Press the shutter-release button on the remote control all the way down.
Shooting ends automatically after about 30 minutes.
A
Self-timer Mode
In self-timer mode, a shutter speed of "Bulb" is equivalent to approximately
1
/ s.
10
t
73