Nikon D780 DSLR Camera (Body Only) - Manual (Page 233)

187 Shooting Settings
ISO Sensitivity
The camera’s sensitivity to light can be adjusted according to
the amount of light available. Choose from settings that range
from ISO 100 and ISO 51200. Settings of from about 0.3 to 1 EV
below ISO 100 and 0.3 to 2 EV above ISO 51200 are also
available for special situations. The higher the ISO sensitivity,
the less light needed to make an exposure, allowing higher
shutter speeds or smaller apertures.
Adjusting the Camera’s Sensitivity to
Light (ISO Sensitivity)