Metering modes. What exactly is the difference, and how to choose which mode to use. A basic overview to assist with exposure and creative decision making.
Take a moment to contemplate the metering modes. Matrix, Center Weighted and Spot are the various metering modes on most cameras. First, lets take a look at each metering mode and explore the differences.
Matrix metering is the default mode on most digital cameras. This mode works by dividing the frame up into multiple zones and analyzing highlights and shadows, as well as overall brightness and contrast. This mode is usually best for landscapes and portraits. It is important to keep in mind that exposure readings are based on the focus point. Generally speaking, Matrix metering is an all auto mode and yields an accurate exposure in a wide variety of lighting situations.
Center Weighted metering
Center Weighted metering was the standard system in cameras prior to matrix metering. In this mode, the exposure is mostly calculated with an emphasis on the middle of the frame, or where the focus point is, but also takes into account some information from the edge of the frame. Think of this as a larger spot meter. In short, if the detail in the center or the focus area is the interest in the image that you are creating this is the mode to use. Center weighted metering will allow for detail in the center and not let highlights or shadows affect the exposure.
Spot metering is my personal favorite! In this mode the exposure is calculated from one tiny area. The highlights and shadows in the rest of the frame are not calculated. This mode is useful as above to create drama, or maintain detail in an exact area. Some cameras allow the user to adjust the size of the meter. The exposure in this case is calculated for detail in the dials. In contrast, if matrix mode had been used much more of the detail in the surrounding areas would be visible, and the lighting overall not as dramatic.
In summary, what mode is best? That all depends on what you, the eye and brain behind the camera, are attempting to show to the viewer. As always, take a moment to really contemplate the why when capturing an image. Where is the detail, and what are you trying to say. Experiment with the various metering modes, and let the creativity grow!