As a photographer, digital or otherwise, one thing that you need to have a good idea of is the camera metering mode. By metering, I am referring to the process of assessing the light that is reflected off a surface and then the evaluation of the right exposure values for a properly exposed picture. All modern digital cameras employ the reflected light method when it comes to metering a scene; meaning, it actually measures how much light is reflected and not how much light falls on it. This process has its own limitations, but, we shall not be delving deeper into that. Here, however, we shall be looking at how to use the right metering mode for a given scene.
Types of metering mode in a modern DSLR
There are three types of metering modes in a standard DSLR. These are matrix metering, spot metering and center-weighted metering. These are the standard names used by Nikon. Canon uses the terms evaluative, spot and center-weighted average metering system. There is a fourth metering system in Canon DSLRs. It is named partial metering. Now, don’t get confused with the different names and acronyms because different manufacturing companies use different terminology. At the end of the day they are the same. Let’s get deeper into each of the metering modes.
Matrix / Evaluative metering mode
Matrix metering or Evaluative metering is a mode wherein light hitting the sensor from all areas of the scene is considered when assessing the right exposure values. Modern DSLR cameras use complicated metering algorithms which are way smarter than the older cameras of yesteryears. They take into account tonal range, color and other parameters. Today’s 3D matrix metering systems also use distance data which further enhance the preciseness of the process. More times than not they accurately determine the right exposure values for even difficult lighting conditions, where intermittent patches of highlights and shadows make manual metering very difficult.
Why would you want to use matrix / evaluative metering?
This is by far the most sophisticated metering mode available on modern DSLR cameras. In fact it is also the most dominant being pre-programmed on all Point & Shoot cameras as well. If you are a landscape photographer this is the best metering mode to use if you don’t have graduated neutral density filters on you. Even if you do, this mode allows you the best possible results because it takes into account the entire frame when evaluating the exposure values.
Spot metering uses a tiny fraction of the frame for metering purposes which is only about 3-5% of the whole frame. It is centered on the focusing point that you select. This means you can move the point of focus and meter an off center composition perfectly. Spot metering ignores the rest of the frame for metering purposes. You would be wondering whether such a thing could have a use. You will realize that it does once you read the next paragraph.
Imagine a scene where you want to focus on something very specific and deliberately over-expose (or under-expose) the rest of the frame. Let’s say you are photographing a baby and you want to deliberately expose properly the eye closest to the camera. You set up the scene, use a lot of light plus a white background. When you meter for the eye, the rest of the frame will be over-exposed giving you a high-key result.
Of course there could be other applications as well such as when you need to make an off center composition. So, feel free to experiment.
Partial metering is unique to Canon systems. Nikon systems don’t come with this mode. You would be wondering why all the time only Nikon and Canon systems are discussed? What about other systems like Sony or Fuji? Well, Nikon and Canon are the two largest DSLR manufacturing companies. Sony and the rest does have a presence, but that is nowhere near as dominant as the other two.
Coming back to partial metering, this mode is much like spot metering, which we learnt above, except that here the camera uses a slightly larger area for evaluating the correct exposure. Also, the area used for metering is at the center of the frame. You cannot move it around like spot metering. This makes it ideal for shooting portrait images. Of course you can also use it for shooting smaller subjects that are at the center of the frame.
Center-weighted metering is like a combination of both evaluative and spot metering but with a slight tweak. In this mode, the camera takes into account the whole of the frame for exposure calculation, but, the center of the frame is given a priority. This makes it ideal for a number of photo opportunities including portraits, group shots and wildlife photos.