Digital SLRs and some compact digital cameras offer different types of metering modes: multi-segment, center-weighted average metering, spot metering, partial metering and auto-exposure lock. For example, I used the exposure lock mode for this sunset photograph that I took in Rajasthan, India. I pointed my camera at the area surrounding the sun and depressed the shutter release half way. That locked the exposure setting—the ƒ/stop and shutter speed. I recomposed the shot with the camel and rider in the frame, then I snapped the shot.
In this article, I’ll give you an overview of metering modes. Each one has its advantages. If you know which mode to choose in a particular lighting situation, you’ll have a good chance of getting a perfect exposure. And keep in mind that different model cameras feature different types of metering modes, and not all digital cameras offer all the modes I’ll discuss.
Multi-segment metering, also called evaluative, matrix or honeycomb metering, is an advanced TTL (through-the-lens) metering system that interprets simultaneous readings from multiple areas in the frame to determine the correct exposure.
It’s ideally suited for quick shooting when you need to get a light reading on an entire scene and set the exposure in a hurry. It can also be good to use when there’s a lot of contrast between light and shadow in a scene, as illustrated in this picture I took on the Ponderosa Ranch. On some cameras, this mode not only measures light, but it can identify some challenging situations (such as backlighting) and, therefore, automatically adjusts the exposure. Furthermore, on some cameras, this metering mode “knows” where your primary subject is located in the frame, because many multi-segment metering systems are linked to the camera’s autofocus system.
So, multi-segment metering is a good choice in many situations, because it evaluates the different areas of the scene and selects the best exposure.
Center-Weighted Average Metering
Center-weighted average metering gives special emphasis to the center of the frame, but also covers the surrounding area. Some photographers prefer this metering mode because it’s simpler and more predictable than multi-segment metering, which uses complex algorithms to sort through the data from all the different points of measurement.
Center-weighted metering is a good mode to select when you want to capture a brightly lit subject and be sure it’s exposed correctly compared with the surrounding areas. This is an excellent compositional technique because people’s eyes are always drawn to the brightest part of a photograph.
Unlike multi-segment metering, which interprets virtually the entire picture area, center-weighted metering does not attempt to identify and correct situations like backlighting. This means you have to be a bit more careful when using this type of metering.
However, many experienced photographers prefer this mode because they can apply their own exposure compensation (+ and –) and know that the camera hasn’t automatically tried to do likewise. I used this mode for this picture of Dead Horse Point State Park in Utah.
Spot metering measures only a small area in the center of the frame. Typically, this area is a spot that’s only about two or three percent of the entire area of the picture (hence the term “spot” metering). When you have a select area of a picture that you want to precisely meter, and don’t want other areas of the scene to affect your exposure, such as this polar bear that I photographed in the sub-Arctic, this mode is the way to go. However, it can be a challenging metering mode to use because you really have to pay attention to exactly what it is measuring and interpret the brightness of the spot yourself.
The size of the spot varies from camera to camera, with high-end cameras usually having a smaller spot than entry-level cameras.
Partial metering covers an area exclusively at the center of the scene, taking up about 10 percent of the total picture area—not quite as small as that of a spot meter. Here, too, if the surrounding area is darker or lighter than the main subject, this mode is a good choice. It will usually give you the correct exposure for your subject, as long as your subject isn’t very light or very dark. That’s why I selected the partial metering mode for this shot of a cowboy riding at sunset at the Ponderosa Ranch in Oregon.
Not all cameras have spot-metering mode. For those that don’t, they’ll typically offer a partial-metering mode instead.
Some digital cameras feature an exposure lock as part of the autoexposure metering system, which is extremely useful for scenes with a high contrast between the light and dark areas. One way to use this feature is to point your camera at an area of a scene that’s a middle brightness or midtone. Once you activate the autoexposure lock mode (AEL), depress the shutter release half way and lock in that exposure. Then you can recompose the scene and take the picture with that setting.
For my photograph of the camel and rider in Rajasthan, India, a balanced exposure was not my goal. I just wanted to capture their shadowed silhouette, illuminated by the radiance of the setting sun. That’s why I pointed my camera at the area surrounding the sun and not at the camel and rider.
This mode also helped me get a good shot of this owl in Upstate New York.
Using another metering mode could have easily underexposed the owl or overexposed the sky. So choose your exposure mode wisely before you shoot. This will ensure that you capture the best images possible and have minimal problems when editing them.
Rick Sammon has published 27 books. Visit www.ricksammon.com for more information, and meet up with Rick at one of his PCPhoto/Outdoor Photographer workshops.