The next picture-taking setting to consider is the exposure mode, which you select via the Mode dial, shown in Figure 2-6. Your choice determines how much control you have over two critical exposure settings — aperture and shutter speed — as well as many other options, including those related to color and flash photography.
Before attempting to rotate the Mode dial, press and hold the lock-release button in the center of the dial, labeled in the figure. Release the button to lock the dial. (This feature avoids the potential that you'll accidentally change the Mode with an errant touch of the dial.)
Your exposure mode choices break down as follows: