Nikon D3300 - Manual (Page 339)

319 Technical Notes
8
Turn the camera off.
The mirror will return to the down position and the shutter
curtain will close. Replace the lens or body cap.
A
Use a Reliable Power Source
The shutter curtain is delicate and easily damaged. If the camera
powers off while the mirror is raised, the curtain will close
automatically. To prevent damage to the curtain, observe the
following precautions:
• Do not turn the camera off or remove or disconnect the power source
while the mirror is raised.
• If the battery runs low while the mirror is raised, a beep will sound
and the self-timer lamp will flash to warn that the shutter curtain will
close and the mirror will be lowered after about two minutes. End
cleaning or inspection immediately.