Sensitivity
“Sensitivity” refers to the camera’s sensitivity to light. Sensitivity is adjusted by pressing the dial lock release and rotating the sensitivity dial; 
choose from values between 200 and 6400, or select L (100), H1 (defaults 
to 12800), or H2 (defaults to 25600) for special situations. Higher values 
can be used to reduce blur when lighting is poor, while lower values 
low slower shutter speeds or wider apertures in bright light; note, how-
ever, that mottling may appear in pictures taken at high sensitivities, particularly at H2, while choosing L reduces dynamic range. Values of from ISO 200 to ISO 6400 are recommended in most situations. If A (auto) is selected, the camera will adjust sensitivity automatically in response to shooting conditions.
RRAW images can not be recorded at settings of L, H1, or H2. Only JPEG images will be recorded if these settings are chosen when RAW, FINE+RAW, or NORMAL+RAW is selected for image quality (P79).
RThe NISO DIAL SETTING option in the setup menu can be used to choose the sensitivity assigned to the H1 and H2 positions on the sensitivity dial (P91). Choose from 12800, 25600, and 51200.
50