Nikon D5000 D5000 User's Guide (English) - Page 167

ISO Sensitivity Settings Adjust ISO sensitivity (0 74). G button ➜ C shooting menu ❚❚ ISO Sensitivity Auto Control If Off is chosen for ISO sensitivity auto control in P, S, A, and M modes, ISO sensitivity will remain fixed at the value selected by the user (0 74). When On is chosen, ISO sensitivity will automatically be adjusted if optimal exposure can not be achieved at the value selected by the user (flash level is adjusted appropriately). The maximum value for auto ISO sensitivity can be selected using the Maximum sensitivity option in the ISO sensitivity auto control menu (choose lower values to prevent noise; the minimum value for auto ISO sensitivity is automatically set to ISO 200). In modes P and A, sensitivity will only be adjusted if underexposure would result at the shutter speed selected for Minimum shutter speed. Slower shutter speeds will be used only if optimum exposure can not be achieved at the ISO sensitivity value selected for Maximum sensitivity. If the ISO sensitivity selected by the user is higher than the value selected for Maximum sensitivity, the value selected for Maximum sensitivity will be used instead. When On is selected, the viewfinder shows ISO-AUTO and the information display ISO-A. These indictors blink when sensitivity is altered from the value selected by the user. i A Auto ISO Sensitivity Control Noise is more likely at higher sensitivities. Use the High ISO NR option in the shooting menu to reduce noise (0 151). 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 SB-900, SB-800, SB-600, and SB-400 flash units), possibly preventing the camera from selecting slow shutter speeds. 149