Nikon D3100 Reference Manual page 73

D
The AF-Assist Illuminator
If the subject is poorly lit, the AF-assist illuminator will light
automatically to assist the autofocus operation when the shutter-
release button is pressed halfway. The AF-assist illuminator will not
light:
• In live view or during movie recording
• During manual focus or if live view is off and continuous-servo
autofocus is selected (AF-C selected for focus mode, or
continuous-servo AF selected in AF-A focus mode)
• If the center focus point is not selected in c Single-point AF, d Dynamic-area AF, or
f 3D-tracking (11 points) AF-area mode (0 58, 60)
• In shooting modes in which the AF-assist illuminator can not be used (0 186)
• If Off has been selected for the AF-assist option in the shooting menu (0 134)
The illuminator has a range of about 0.5–3.0 m (1 ft. 8 in.–9 ft. 10 in.); when using the
illuminator, use a lens with a focal length of 18–200 mm and remove the lens hood. The AF-
assist illuminator will turn off automatically to protect the lamp after a period of continuous
use. Normal function will resume after a brief pause. Note that the illuminator may become
hot when used multiple times in quick succession.
A
The Beep Speaker
The Beep option in the setup menu (0 144) can be used to turn the beep speaker on or off.
AF-assist illuminator
z
57