Depth of Field

Depth of Field Demonstration

In this experiment, the camera was set to Aperture Priority (Av) mode and the camera was focused on the same point for each shot. The first photograph was taken with an aperture setting of f/4.5, and the aperture was narrowed on each successive shot.

The experiment showed that decreasing the size of the aperture by setting a higher f number would make a greater area of the photo appear in focus, known as 'increasing the depth of field'. Conversely, using a wider aperture makes parts of the photo appear blurred. The technique is often used for emphasis, to control which parts of an image receive the most attention. When areas of a scene are out of focus, a viewer is less likely to notice them, concentrating instead on the sharper elements that can be more easily identified.

Aperture f/4.5
At a setting of f/4.5, only the middle fence post is sharp.

Aperture f/8
At f/8 the depth of field extends to the posts on either side.

Aperture f/16
At f/16, most of the fence appears sharp, but the grassy bank behind it is still blurred.

Aperture f/32
At f/32 most of the image appears sharp, with the exception of some of the trees in the background