The majority of SLR camera's will give you a choice of at least three different metering systems. The names of the modes will differ depending on your camera model.
•Matrix metering on Nikon camera's is called either Pattern or Evaluative on other models.
•Most brands all name the second mode, Center-weighted metering or very close to it.
•Whereas Spot metering found on Nikon SLR's, basically work similar to Partial metering on Canon digital camera's.
When to use Matrix (Pattern, Evaluative) metering modes
Matrix, Pattern and Evaluative are considered good all-round metering modes. The camera sets the exposure automatically to suit the scene, taking into consideration both dark and light area's. It's considered good for evenly backlit subjects like portraiture and landscapes. It's also the way to go when you're not sure which metering mode to use. This is the reason why it's the default setting for fully automatic camera settings.
Matrix metering works by dividing the frame into zones, taking separate readings from each one. The camera then takes a guess at what parts of the scene are important and exposes accordingly. For the most part, it does a pretty good job at picking the correct exposure.
When to use Center-weighted metering
Center-weighted metering assigns the greatest weight for exposure from the middle area of the frame. Therefore, it's good for times when your main subject is in the middle of the frame and you want to take a quick exposure.
Center weighted metering would be effective when you have a bright background or backlit subject. For example, if you were taking a photograph of a persons face on a sunny day at the beach. You wouldn't want the strong background light, or the white sand, to effect the exposure on their face. As long as the persons face was correctly exposed, that's all that matters. It's times like this, you would choose center weighted metering.
When to use Spot or Partial metering
Spot (Nikon) or Partial (Canon) metering should be used when you want to take an exposure reading on a specific area. It takes the reading from a very small area in the middle of your composition.
You would use spot or partial metering for example, if you had a slightly shaded white bird, against a darker background. You would then take the exposure from the birds feathers and the darker background wouldn't effect the coloring.
