Canon T3i Experience

determine proper exposure of a subject or scene before switching the camera to Manual Mode for a controlled studio shot, a critical shot, or a series of shots where the lighting is not going to change.

3.6d Center-Weighted Average Metering

This metering mode can be thought of as a combination of Evaluative and Partial Metering. It acknowledges that the subject is in the center and requires special metering attention, but it also takes into account all the other exposure metering zones. This mode is useful where there is a difference in lighting between the foreground or subject and the background, but unlike Spot or Partial Metering you still wish for the camera to take both subject and background exposure into consideration (see Figure 17).

As with Spot or Partial Metering, this might be used when your subject is backlit, or when a nicely lit subject is in front of a darker or lighter background. Another time to use this is when there is a wide range of light in your scene, such as bright sunlight to deep shadows. Determine the proper exposure by metering on the subject using the center of the viewfinder, and lock in that exposure (see Exposure Lock below).

Again, this is not linked to the active autofocus AF point, but always to the center, so if your subject is off center - which it typically should be for a more dynamic image - you need to lock the exposure on your subject and then recompose. If you are finding that Evaluative Metering is not giving you the exposures you desire because you are always seeking out and using unusual, dramatic, or difficult lighting, and your exposures are consistently slightly too dark or too light, try using Partial Metering or Center-Weighted Average Metering in conjunction with Exposure Lock. Or use Exposure Compensation, discussed below.

Center-Weighted, Partial, or Spot?

To decide between Center-Weighted Metering and Partial Metering: use Partial Metering in a high-contrast situation where you want to properly meter on the subject but don’t want an extremely bright or dark background to influence the exposure (see Figure 15). Use Center-Weighted Metering in a situation where you want to ensure the subject is properly metered, but the background or other areas of the image are also somewhat important for the metering system to consider, and aren’t so light or dark compared to the subject that they will throw off the exposure (see Figure 17). Use Spot in a similar manner to Partial, except that you need to meter on even a smaller area for more precision (see Figure 16).

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