Adjust ISO sensitivity (0 ISO Sensitivity).
Auto ISO Sensitivity control
This option is available with type E and G lenses (0 Identifying CPU and Type G, E, and D Lenses) when the camera is in P, S, A, or M mode. If Off is selected, ISO sensitivity will remain fixed at the value selected by the user (0 ISO Sensitivity). When On is chosen, ISO sensitivity will automatically be adjusted if optimal exposure cannot be achieved at the value selected by the user. The maximum value for auto ISO sensitivity can be selected using the Maximum sensitivity option in the Auto ISO sensitivity control menu (choose lower values to prevent noise (randomly-spaced bright pixels, fog, or lines), but note that if the ISO sensitivity selected by the user is higher than that chosen for Maximum sensitivity, the value selected by the user will be used instead; the minimum value for auto ISO sensitivity is automatically set to ISO 100). In modes P and A, sensitivity will only be adjusted if underexposure would result at the shutter speed selected for Minimum shutter speed (1/2000–30 s, or Auto; in modes S and M, sensitivity will be adjusted for optimal exposure at the shutter speed selected by the user). If Auto is selected, the camera will choose the minimum shutter speed based on the focal length of the lens. Slower shutter speeds will be used only if optimal exposure cannot be achieved at the ISO sensitivity value selected for Maximum sensitivity.
When On is selected, the viewfinder shows ISO AUTO and the information display ISO-A. These indicators flash when sensitivity is altered from the value selected by the user.
Maximum Sensitivity/Minimum Shutter Speed
When auto ISO sensitivity control is enabled, the ISO sensitivity and shutter speed graphics in the information display show the maximum sensitivity and minimum shutter speed.
Auto ISO Sensitivity Control
Note that ISO sensitivity may be raised automatically when auto ISO sensitivity control is used in combination with slow sync flash modes (available with the built-in flash and the optional flash units listed in “CLS-Compatible Flash Units”, 0 CLS-Compatible Flash Units), possibly preventing the camera from selecting slow shutter speeds.