AF-Assist Illuminator

Nikon D7000 AF-assist illuminatorExplanation: The small white lamp next to the shutter release button lights up if the ambient light is possibly too low for the autofocus and if you have not deactivated it in the custom setting menu a7 Built-in AF-assist illuminator.

Additionally it will light up if the flash is set for red-eye reduction and it will blink while the self-timer is counting down.

Tips: I usually leave it on unless the light is disrupting. Taking photos without the light is more discrete and the autofocus works still fine in many situations where the camera would switch on the additional light.