Choosing an Exposure Metering Mode on a Canon EOS Rebel T3 Series Camera
The metering mode determines which part of the frame the camera analyzes to calculate the proper exposure. The Canon Rebel T3 and T3i offer four metering modes. However, you can access all four modes only in the advanced exposure modes (P, Tv, Av, M, and A-DEP) and only during regular, through-the-viewfinder shooting. In Live View mode, as well as in the fully automatic exposure modes, you’re restricted to the first of the four modes, Evaluative metering.
Evaluative metering: The camera analyzes the entire frame and then selects exposure settings designed to produce a balanced exposure.
Partial metering: The camera bases exposure only on the light that falls in the center 9 percent of the frame.
Spot metering (T3i only): This mode works like Partial metering but uses a smaller region of the frame to calculate exposure. For Spot metering, exposure is based on just the center 4 percent of the frame.
Center-Weighted Average metering: The camera bases exposure on the entire frame but puts extra emphasis, or weight, on the center.
In most cases, Evaluative metering does a good job of calculating exposure. But it can get thrown off when a dark subject is set against a bright background or vice versa.
Use either of these two options to change the metering mode:
Quick Control screen: After displaying the screen, highlight the option shown on the left. The selected setting appears in the label at the bottom of the screen. Rotate the Main dial to cycle through the four modes or press Set to display a list of all four modes, as shown on the right. If you take the second route, use the cross keys or Main dial to highlight the icon for the mode you want to use and then press Set to lock in your decision.
Shooting Menu 2: You also can find the metering mode option here.
In theory, the best practice is to check the metering mode before each shot and choose the mode that best matches your exposure goals. But in practice, it’s a pain, not just in terms of having to adjust yet one more setting but also in terms of having to remember to adjust one more setting. So until you’re comfortable with all the other controls on your camera, just stick with Evaluative metering. It produces good results in most situations, and after all, you can see in the monitor whether you like your results and, if not, adjust exposure settings and reshoot. This option makes the whole metering mode issue a lot less critical than it is when you shoot with film.