Photography 101: Aperture and Depth of field {DOF}

Depth of Field (DOF) is that amount of your shot that will be in focus.

Depth of field is governed by three factors: aperture, lens focal length and shooting distance.
*The smaller the aperture, the deeper the depth of field (the other two factors remaining the same).
*The shorter the lens focal length, the deeper the depth of field (the other two factors remaining the same).
*The greater the shooting distance, the deeper the depth of field. i.e. other two factors remaining the same).

There are times when you desire a great depth of field, i.e. where objects both close to you and far from you are in focus. This is especially true when you are taking a landscape picture and want as much as possible to be in crisp focus.
Large depth of field means that most of your image will be in focus whether it’s close to your camera or far away where both the foreground and background are largely in focus.

Then there are times when you want to isolate your subject, as when you are taking a portrait and want your subject to be in sharp focus but the background to be out of focus. In this case, you desire a shallow depth of field.

One way to influence DOF is by selecting the appropriate aperture.

The rule of thumb is this:

Select a large aperture (or small f/value or small aperture value), e.g. f/2.8, to obtain a shallow DOF
Select a small aperture (or large f/value or large aperture value), e.g. f/8.0, to achieve great DOF


Small (or shallow) depth of field means that only part of the image will be in focus and the rest will be fuzzy).
DOF also changes with focal length. Use a small focal length to increase DOF, a longer focal length obtain a shallower DOF.

Aperture and the Sweet Spot - sweet spot is the place where the lens is in its sharpest point. For most lenses (that go on DSLRs) this is somewhere between f/8 and f/11. Remember that when looking for sharpness in your picture.