The metering mode determines which part of the frame the Canon EOS 60D analyzes to calculate the proper exposure. The EOS 60D offers four metering modes. However, you can access all four modes only in the Creative Zone 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. The 60D evaluates the exposure of all the metering zones (factoid: there are 63 of them!), including the nine AF points during the process.
Partial metering: The camera bases exposure only on the light that falls in the center 6.5 percent of the frame. The left image provides a rough approximation of the area that factors into the exposure equation.
Spot metering: 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 2.8 percent of the frame.
Center-Weighted Average metering: The camera bases exposure on the entire frame but puts extra emphasis (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.
Of course, if the background is very bright and the subject is very dark, the exposure that does the best job on the subject typically overexposes the background. You may be able to reclaim some lost highlights by turning on Highlight Tone Priority.
Use either of these two options to change the metering mode:
Quick Control screen: First, display the Shooting Settings screen by pressing the shutter button halfway and then releasing it. Then press the Quick Control button to shift into Quick Control mode and use the multicontroller to highlight the Metering mode icon. 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. If you take the second route, use the multicontroller or the Main dial to highlight the icon for the mode you want to use and then press Set to lock in your decision.
Metering mode selection button: Press the Metering mode selection button. Highlight your choice and press Set again to return to the menu.
In theory, the best practice is to check the metering mode before each shot and choose the mode that best matches your exposure goals.