Depth of Field

When you focus on something, subjects at other distances may look sharp in the picture or they may not look sharp. Each aperture actually produces a range of sharpness called depth of field. This range expands and contracts with different apertures. Knowing how to control depth of field is a very creative tool.

Short apertures produce greater depth of field, in situations where you lots of sharpness, from nearby objects to far away objects. A small aperture will range from F/16 to F/22.

A large aperture such as a setting of F/2.8 will tend to keep the subject (close up) in focus, however the background will become blurred (out of focus). The range of sharpness is much less.

If you were taking a landscape picture you would more than likely use a small aperture (F/16 - F/22). This would allow the foreground and background to remain in focus and produce a sharp detailed photograph. Also a wide-angled lens would be most appropriate to maximize depth.

A large aperture (F/2.8) would be needed if you where taking a portrait or a close-up photo. This would isolate the subject from it`s background. By doing this you would have the background out of focus (blurred) thus keeping the eye on the important subject which is focused and vivid.