Auto ISO Sensitivity Control
If On is selected for ISO sensitivity settings > Auto ISO sensitivity control in the photo shooting menu, ISO sensitivity will automatically be adjusted if optimal exposure cannot be achieved at the value selected by the user (ISO sensitivity is adjusted appropriately when the flash is used).
Select Auto ISO sensitivity control.
Select ISO sensitivity settings in the photo shooting menu, highlight Auto ISO sensitivity control and press 2.
Highlight On and press J (if Off is selected, ISO sensitivity will remain fixed at the value selected by the user).
The maximum value for auto ISO sensitivity can be selected using Maximum sensitivity (the minimum value for auto ISO sensitivity is automatically set to ISO 64; 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). In exposure modes P and A, sensitivity will only be adjusted if underexposure would result at the shutter speed selected for Minimum shutter speed (1/4000–30 s, or Auto; in modes S and M, ISO 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; choosing fast speeds when photographing fast-moving subjects reduces blur. Press J to exit when settings are complete.
To choose the maximum ISO sensitivity for photos taken using an optional flash unit, use Maximum sensitivity with M. Selecting Same as without flash sets the maximum ISO sensitivity for flash photography to the value currently selected for Maximum sensitivity.
When On is selected, the viewfinder and control panel show ISO AUTO. When sensitivity is altered from the value selected by the user, these indicators flash and the altered value is shown in the viewfinder and control panel.
Minimum Shutter Speed
Auto shutter-speed selection can be fine-tuned by highlighting Auto and pressing 2: for example, values faster than those usually selected automatically can be used with telephoto lenses to reduce blur. Note, however, that Auto functions only with CPU lenses; if a non-CPU lens is used without lens data, minimum shutter speed is fixed at 1/30 s. Shutter speeds may drop below the selected minimum if optimum exposure cannot be achieved at the ISO sensitivity chosen for Maximum sensitivity.
Turning Auto ISO Sensitivity Control On or Off
You can turn auto ISO sensitivity control on or off by pressing the S (Q) button and rotating the sub-command dial. The control panel and viewfinder display ISO AUTO icons when auto ISO sensitivity control is on and ISO when it is off.
Auto ISO Sensitivity Control
When a flash is used, minimum shutter speed will be set to the value selected for Minimum shutter speed unless this value is faster than Custom Setting e1 (Flash sync speed, 0 Flash Sync Speed) or slower than Custom Setting e2 (Flash shutter speed, 0 Flash Shutter Speed), in which case the value selected for Custom Setting e2 will be used instead. Note that ISO sensitivity may be raised automatically when auto ISO sensitivity control is used in combination with slow sync flash modes (available with compatible optional flash units), possibly preventing the camera from selecting slow shutter speeds.
For information on choosing the reference used to set exposure when a flash is used with auto ISO sensitivity control, see A > Custom Setting e4 (Auto M ISO sensitivity control, 0 Auto M ISO Sensitivity Control).