Examples of exposure metering fooled

Here are some photos to illustrate how the camera metering system can be fooled by extremely light or dark scenes.  The camera assumes that the scene is a medium gray (the meter works in grayscale not color) and tries to exposure the scene so that the medium gray is properly exposed.  In these photos, I determined proper exposure by using the camera's evaluative (or matrix) metering setting.  One stop underexposed is equivalent to -1 in exposure compensation.  One stop overexposed is equivalent to +1 in exposure compensation. You can click on the photo to enlarge it.

A brick wall is a medium dark color, so the camera meter gets the right exposure.  As we can see below, the "properly exposed" shot looks best.


One stop underexposed

Properly exposed

One stop overexposed

A white scene (for example, snow or ice) will cause the camera to underexpose the scene.  The camera thinks the white is too bright and tries to reduce exposure.  If you encounter a very light scene, you should set your exposure compensation to be positive.  As we can see below, the "overexposed" shot looks best.  (In this case, the camera metering didn't quite do what I expected.  The best exposure might be in between the "properly exposed" and "overexposed" shots.)



One stop underexposed

Properly exposed

One stop overexposed

A very dark scene will cause the camera to overexpose the scene.  The camera thinks that the scene is too dark and tries to increase exposure.  If you encounter a very dark scene, you should set your exposure compensation to be negative.  As we can see below, the "underexposed" shot looks best.



One stop underexposed

Properly exposed

One stop overexposed