Nikon D6 User Manual With Warranty page 173

"Noise" (bright spots, randomly-spaced bright pixels, fog, or
●
lines) appears in photos:
•
To reduce noise, adjust settings such as ISO sensitivity, shutter
speed, or Active D-Lighting.
•
At high ISO sensitivities, noise may become more noticeable in long
exposures or in pictures recorded when the camera temperature is
elevated.
Problems and Solutions
143