To adjust shutter speed manually while letting the camera select aperture for optimal exposure, set aperture to A and use the shutter speed dial (if A is currently selected for shutter speed, press the dial lock release while rotating the shutter speed dial).
S will appear in the display.
Shutter speed can also be adjusted in increments of 1/3 EV by rotating the front command dial. Shutter speed can be adjusted even while the shutter button is pressed halfway.
If the correct exposure can not be achieved at the selected shutter speed, aperture will be displayed in red when the shutter button is pressed halfway. Adjust shutter speed until the correct exposure is achieved.
If the subject is outside the metering range of the camera, the aperture display will show “---”.