Camera Metering Modes Explained | PetaPixel

One of the many features that modern cameras have is a selection of exposure metering modes. This allows you to choose how the camera measures the brightness of a subject or scene in order to automatically adjust camera settings for optimal exposure.

In this article, we’ll explain what camera metering modes are and how to use them.

Table of contents

What is exposure measurement?

Metering is simply the camera’s process of checking the amount of light reflected in a scene and calculating the appropriate exposure settings (i.e. shutter speed, aperture and/or ISO sensitivity) based on that information. The camera will indicate an 18% reflection of a certain gray (AKA “medium gray”) as normal exposure, and will attempt to adjust the exposure settings in such a way that the resulting image reflects that normal exposure.

While this tactic works well with a wide range of everyday subjects and scenes, there are sometimes situations where this strategy does not produce the desired results. For example, snow scenes are known to be very difficult for auto-exposure systems on cameras to detect – an image of snow will generally be overexposed by the camera because it will attempt to reduce the white values ​​of the snow to match the average gray. Likewise, a scene that is predominantly black may be overexposed due to the camera attempting to increase black values ​​to medium gray.

Gray card is a photographic accessory that can help photographers achieve adequate exposure even when dealing with difficult lighting. It can help photographers to create mirrored composite images, focus stacking, and other applications where multiple images need to be combined.

Gray card and color scheme

Due to the wide range of subjects and scenes a photographer may encounter, there are different ways a camera can use a standard exposure metering strategy to evaluate a scene. This is why metering modes exist. Each one tells the camera how and where it should take a reading of 18% gray.

There are typically three basic measurement modes found in cameras: evaluative, central weighed, and spot. Depending on the brand of the camera, one may encounter other names and metering patterns, including matrix, micro-metering, highlight-weighted, multi-mode, and full-screen average metering.

Canon DSLR Camera
Selecting the metering mode on a Canon DSLR camera.

Let’s go through the options out there mode by mode and see what they do.

Evaluative measurement

Discretionary metering (known as matrix metering on Nikon cameras and multi-style metering on Sony cameras) is most popular with novice photographers because it is a one-size-fits-most approach. What this mode does is divide the scene into a lot of squares and rate each one for the presence of 18% gray (and sometimes other factors, such as color).

Instead of giving all pieces equal importance, the camera slightly prioritizes the area that the autofocus is set to when calculating exposure settings in hopes of correctly exposing the intended subject. The weighted average of the squares is what the camera uses to determine the exposure.

Evaluative scaling is a good default option because it can really be used for most scenes and genres: anything from wildlife to portraits to landscapes to fashion. It aims to strike a good balance between the light and dark parts of the scene.

The camera was able to detect the appropriate exposure for this Oxford Street scene, balancing the brighter areas of the sky and the darker areas of the street and buildings below.

Estimated scaling may not be appropriate in scenes with unusual lighting where the environment is very light or dark.

Center measurement

Center-weighted metering mode is great for photos where your subject is in or near the center of the frame, because this is the area the camera will base exposure setting calculations on. It will ignore the gray level at the edges and consider only the tones in the center.

For example, if someone is taking a concert photo where the surroundings are mostly black but the center is bright, this mode will help properly overexpose the performers on stage while the rating may overexpose the scene.

It can also be a great option for taking selfies.

Know that this mode is weighted toward an area in the center of the frame and not for accurate scaling based on a specific point in the scene.

spot metering

Spot metering is for accurately calculating the appropriate exposure based on only the small area of ​​the selected focus point. Resolution range may vary depending on the camera used, but often takes into account only 1.5% to 2.5% of the scene.

This will probably be the mode you would use to photograph a bright moon on a cloudless night or a dark bush in a snowy landscape. It will only measure your small subject and ignore the rest of the scene which could cause underexposure or overexposure in wider metering modes.

When spot metering is exposed to the black square, the camera will ignore (and overexpose) the rest of the scene because it prioritizes bringing black values ​​to 18% gray.

Spot metering pairs well with the auto exposure lock feature/button on cameras, which freezes exposure settings. The photographer can point to the focus point at a specific meter position and lock the exposure settings before reconfiguring the desired composition.

Partial measurement

Micro metering, found in Canon cameras, is very similar to spot metering except that it measures a slightly larger area (eg 6.5% of the scene around the focus point vs 2.5%). This mode is a good choice when

Wildlife and nature photography are good applications of micro-metering, where the subject will occupy a large portion of the frame and when the background is either brighter or darker than the subject.

Due to the relatively large subject size in the frame, I used a partial measurement to correctly show the singer’s face.

The choice between spot and partial scaling usually comes down to the relative size of your subject in the entire frame.

Shading weight

The highlight metering, found in Nikon cameras, has been found to give the highest priority to highlights in the frame to make sure these areas are not blown out.

It is an ideal solution for high contrast images or when the photographer wants to preserve as much detail as possible in the highlights, such as with performers on a stage illuminated by a spotlight.

Full Screen Average Scale

On Sony cameras, full screen average metering is similar to evaluation metering in that it will average the entire scene, but will not prioritize any area around the focus point.

The advantage of this metering mode is that it allows you to keep the exposure settings between frames exactly the same even if the subject moves or if the composition changes (without affecting the overall rate of the scene).

Measuring mode is just a starting point

With modern cameras with crazy dynamic range, it might be reasonable to argue that metering mode is less important than before given how easy it is to get a good final image out of a poorly exposed image by restoring shadow and accentuating detail during post-processing. Although this may have some truth, it is still a good idea to get the initial exposure of the image as “correct” as possible to save editing time and reduce the risk of clipping (overexposing the image or underexposing it to the point where detail is lost in the highlights and shadows, respectively).

If the photographer is shooting in manual mode, the metering mode is no longer important and the photographer can adjust shutter speed, aperture, and ISO sensitivity while trying to achieve exposure based on what the camera says or on the specific look desired.

In addition to selecting a specific metering mode for a difficult scene, photographers also have exposure compensation as a tool for arriving at the proper exposure. For example, when photographing an overwhelmingly black or white scene, the photographer may increase or decrease the final exposure, respectively, using the camera’s exposure compensation feature to “correct” the defective camera metering based on 18% gray.

Here is an example based on a white on white scene:

The white scene is overwhelmingly overexposed by the camera using the exposure settings specified by exposure metering.
Using exposure compensation can correct incorrect camera exposure.

Here is an example based on a black to black scene:

A very black scene is exposed by the camera using the exposure settings determined by the exposure metering.
Using exposure compensation can correct incorrect overexposure of the camera.

conclusion

The photographer must have a good understanding of not only how to use the different metering modes but also how to achieve the desired results when the camera exposure metering faces limitations. As with many subjects in photography, a great way to learn about each pose is to try it in different environments to see how it performs.

Just to recap, the different metering modes give the photographer different degrees of control. One way to find out which metering mode is best is to ask if there is a lot of black-and-white imbalance in the scene being photographed.

For evenly balanced scenes, discretionary metering gives the camera nearly complete control over determining the best exposure settings. When there is an imbalance and the photographer’s input is needed, use spot metering to specifically choose the point in the scene to calculate exposure based on that. Other modes such as partial or midweight provide a good middle ground between camera and photographer control.

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