Your camera has the following metering modes: Digital ESP, Center Weighted Average, and Spot (spot, highlight, and shadow). Why does it matter what metering pattern you use? Limiting the metering area (Center-Weighted or Spot) helps to ensure your most important subject matter is properly exposed. Expanding the metering area (Digital ESP) ensures that the entire image area will be properly exposed.
This is your most often used metering mode. Exposure is based on light levels at the center of the image and the surrounding areas. Some areas are more weighted than others. Digital ESP works well for almost all shooting situations except when there are large, very bright or dark areas in the image area.
ESP\Digital ESP works well for this situation which has a good balance of light to dark.
Use this metering mode for situations when you want to precisely control what your camera bases exposure on -- like a flower in a field. The camera will only base exposure on what it sees at the very center of the image; therefore, the surrounding area won't affect the resulting exposure. You can use the AEL button to lock the meter reading then recompose if necessary.
Spot metering works well for this situation, correctly exposing the small area occupied by the flower and not the dark background.
The HI (highlight metering mode) and SH (shadow metering mode) can be useful to advanced photographers who want to set the tonality of their images. You will achieve tones that are either darker or lighter than an average tone, similar to the result of applying exposure compensation. Use SH spot to reproduce tones that are darker than an average tonality, like a black cat. Use HI spot to reproduce tones that are lighter than an average tonality, like a snow landscape.
SH Spot metering enables the camera to shift to underexposure to produce accurate black reproduction. This is the same as applying exposure compensation of -1. Auto exposure would result in a gray cat.
HI Spot metering enables the camera to shift to overexposure to produce accurate white reproduction. This is the same as applying exposure compensation of +1. Auto exposure would result in a grayish cast to the overall scene.
This metering mode is best when your subject takes up most of the center of the viewfinder with a bright or dark background. Therefore, your subject will be properly exposed regardless of the background.
Center-weighted metering works well for this situation, exposing only the larger center area and not the brighter outer area.
Tip: Set your camera to Digital ESP, your most commonly used metering pattern. Under the Tools 1 menu set AEL Metering to Spot if you would like the AEL button to automatically provide a Spot meter reading as well as act as an exposure lock. If you want it to strictly lock in exposure for the metering mode pattern you have set, select AUTO.