Nikon called matrix mode, while the Canon called evaluative mode. The way it works is to divide all the camera images of objects that exist in the viewfinder into several zones or regions, and each zone was measured dark brightness. The camera also stressed zone where you put the focal point as the critical zone, so that the value of the dark light here is considered as a priority. Once all the information was gathered, the camera will try to determine the exposure value that fits.
In addition, the DSLR camera also compare the brightness above information with shooting data sample in a variety of circumstances that have been put into memory by the manufacturer for determine camera exposure value according to which is most appropriate. Fashion matrix / evaluative commonly used in most normal shooting situations, the most accurate in everyday conditions and the most frequently used. So, before you find the shooting situation is complex and difficult, use this mode.
Center Weighted Metering
Using the whole frame area to determine the exposure value does not always produce the desired image. What about if you want to capture a face with the sun behind it? If you use matrix mode, the face will likely look very dark.
This is when you use center weighted mode. This mode measures light reflection around the midpoint and ignoring the frame area around the corners of the frame. That way the camera will only measure exposure at face value (midpoint viewfinder) and ignores the value in other areas (the sun is much brighter). Compared with the mode matrix, center weighted mode do not see where we put the focus point, he only saw the area around the midpoint of the viewfinder.
Spot / Partial Metering
Spot metering will only measure light around the focus point and ignore other areas of light, rather only about 3% of the measured object photo. While measuring the partial metering area slightly larger, about 10% of the whole picture and also ignore this mode area . Second same principle works. They evaluated a single zone and calculate exposure was purely based on the results of the evaluation, while the other zones are not counted at all.
Examples of its use is when you are photographing a friend to the sun that shines brightly, but the friend is only a small part of the overall picture while we wanted to make sure he measured it with good exposure (not too dark and not too bright). If you use matrix or center weighted metering, most likely our friend will only be seen as a silhouette, because the camera actually measures sunlight that dominate the picture.
Another example is the use of spot metering when we photographed the bird. Because birds (unless you photographed in close-up), fill a small frame then use spot metering to ensure the birds as the main object eksposure appropriately.
How to Change the Metering Mode?
Depending on the type and brand of camera, how to switch the metering mode is quite varied. For Digital SLR cameras class pro and semi-pro, it usually has a dedicated button to change the metering mode. While DSLR camera beginner classes usually in the sub-menu.