The rear command dial is used as described below.
Rotate the dial to adjust aperture, adjust settings in the quick menu, choose the size of the focus frame, or zoom in or out in full-frame or thumbnail playback.
Press the center of the dial to zoom in on the selected focus area or in playback mode to zoom in on the active focus point. In manual focus mode, you can choose a focus display by pressing and holding the center of the dial.
Formatting Memory Cards
To format memory cards, press the center of the command dial while pressing and holding the 
button.
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