About ISO Sensitivity
The camera’s sensitivity to light (ISO sensitivity) can be adjusted according to the amount of light available. In general, choosing higher values allows faster shutter speeds at the same aperture. Choose from settings of from ISO 64 to 25600. Extended settings of from about 0.3 to 1 EV (ISO 32 equivalent) below ISO 64 and 0.3 to 2 EV (ISO 102400 equivalent) above ISO 25600 are also available.
Adjusting ISO Sensitivity
Hold the S (Q) button and rotate the main command dial.
Your selection is shown in the shooting display and control panel.
At default settings, changes to ISO sensitivity are made in increments of 1/3 EV. The size of the increments can be changed using Custom Setting b1 .
The higher the ISO sensitivity, the less light needed to make an exposure, allowing pictures to be taken when lighting is poor and helping prevent blur when the subject is in motion. Note, however, that the higher the sensitivity, the more likely the picture is to be affected by “noise” in the form of randomly-spaced bright pixels, fog, or lines.
“Noise” can be reduced by enabling high ISO noise reduction. High ISO noise reduction can be enabled using the  items in the photo shooting and video recording menus.
ISO senstivity can also be adjusted using the  item in the photo shooting menu.
A setting of  corresponds to an ISO sensitivity approximately 0.3 EV higher than ISO 25600 (ISO 32000 equivalent) and [ ] to an ISO sensitivity approximately 2 EV higher (ISO 102400 equivalent). Note that pictures taken at these settings are particularly prone to “noise” in the form of randomly-spaced bright pixels, fog, or lines.
 corresponds to an ISO sensitivity about 0.3 EV below ISO 64 (ISO 50 equivalent). [ ] is roughly 1 EV below ISO 64 (ISO 32 equivalent). Use for larger apertures or slower shutter speeds when lighting is bright. Highlights may be overexposed. In most cases, ISO sensitivities of ISO [ ] or above are recommended.
Auto ISO Sensitivity Control
Auto ISO sensitivity control automatically adjusts ISO sensitivity if optimal exposure cannot be achieved at the value selected by the user. You can select an upper limit for auto ISO sensitivity control (100–Hi 2.0) to prevent ISO sensitivity being raised too high.
Enabling Auto ISO Sensitivity Control
Hold the S button and rotate the sub-command dial to select from ISO AUTO (auto ISO sensitivity control enabled) and ISO (auto ISO sensitivity control disabled).
When auto ISO sensitivity control is enabled, the shooting display will show ISO AUTO and control panel ISO-A. When sensitivity is altered from the value selected by the user, the ISO sensitivity will be shown in the displays.
Maximum sensitivity can be adjusted using the  item in the photo shooting menu.
If the value currently selected for  is higher than that chosen for [ ], the value chosen for [ ] will serve as the upper limit for auto ISO sensitivity control.
During flash photography, shutter speed is limited to the range defined by the values selected for Custom Settings e1  and e2 [ ]. If the value selected for [ ] is not in this range, the value selected for Custom Setting e2 [ ] becomes the effective minimum shutter speed.
Except in mode M, videos are recorded using auto ISO sensitivity control. Auto ISO sensitivity control can be enabled for video recording in mode M by selecting  for [ ] > [ ] in the video recording menu.