Evaluative metering
■ Spot metering. Exposure is calculated from a smaller central spot, about 3.8 percent of the image area.
■ Center-weighted averaging metering. The T2i meters the entire scene, but gives the most emphasis to the central area of the frame.
You'll find a detailed description of each of these modes in Chapter 4.
Choosing a Focus Mode
You can easily switch between automatic and manual focus by moving the AF/MF switch on the lens mounted on your camera. However, if you're using a Creative Zone shooting mode, you'll still need to choose an appropriate focus mode. (You can read more on selecting focus parameters in Chapter 5.) If you're using a Basic Zone mode, the focus method is set for you automatically.
To set the focus mode, you must first have set the lens to the AF position (instead of the manual focus MF position). Then press the AF button (it's the right cross key) on the back of the camera repeatedly until the focus mode you want is selected (see Figure 1.16). Finally, press Set to confirm your focus mode. The three choices available in Creative Zone modes are as follows:
■ One-Shot. This mode, sometimes called single autofocus, locks in a focus point when the shutter button is pressed down halfway, and the focus confirmation light glows in the viewfinder. The focus will remain locked until you release the button or take the picture. If the camera is unable to achieve sharp focus, the focus confirmation light will blink. This mode is best when your subject is relatively motionless. Portrait, Night Portrait, and Landscape Basic Zone modes use this focus method exclusively.
■ AI Servo. This mode, sometimes called Continuous Autofocus, sets focus when you partially depress the shutter button, but continues to monitor the frame and refo-cuses if the camera or subject is moved. This is a useful mode for photographing sports and moving subjects. The Sports Basic Zone mode uses this focus method exclusively.
■ AI Focus. In this mode, the T2i switches between One-Shot and AI Servo as appropriate. That is, it locks in a focus point when you partially depress the shutter button (One-Shot mode), but switches automatically to AI Servo if the subject begins to move. This mode is handy when photographing a subject, such as a child at quiet play, which might move unexpectedly. The Flash Off Basic Zone mode uses this focus method.
Figure 1.16
Set AF mode.
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