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Once you know this, it becomes very easy to check the image on playback and change the aperture if required to reduce or increase the depth of field. Or even use a button called depth-of-field preview to check this before shooting (if your camera has this it’s usually found near the lens mount)

Exposure and contrast

The accuracy of modern autofocus systems means that the camera usually gets the main subject sharp – although this does require you and the camera to agree on what the subject is! Depth of field, however, means that there’s rather more uncertainty about whether other things in the shot are or aren’t sharp.

There’s a very similar relationship between exposure and contrast. Just as the human eye adjusts focus so fast it gives us an impression of immense depth of field, it can adjust almost instantaneously between deep shadow and bright sunlight. Most of the time we don’t see shadows as completely black or bright objects as totally white. We might call them black or white but we can still see detail within them.