Depth of field may sound technically challenging, but in fact is a relatively simple concept. Depth of field refers to the area of sharpness in the photograph's focal point. As you move out from the center point, the image begins to blur. The area where the image remains sharp is the depth of field, while the blurred area surrounding this is called the “circle of confusion.” By controlling how large your depth of field is, you can draw the viewer's eye to as much or as little as you want.
The two key elements you need to keep in mind when trying to control depth of field are
aperture settings and distance to the object. Being able to adjust these two factors will lead to very specific image results.
Closer shots are the way to go to keep your depth of field small. The close proximity of your camera to the object is important because of the physical limitations of the angle. You can only focus on one area at a time. By placing your camera in a close up the lens will naturally blur everything but the immediate object. This is not the same thing as shooting the object with a telephoto lens. While the zoom shot may at first glance may appear to do the same thing, this shot simply enlarges objects so that the depth of field will be proportionally the same as if shot from a long distance, ruining the specific appearance you may be trying to achieve with a tighter area of focus.
The aperture setting is also key. The larger your aperture the smaller your depth of field. F/8.0 aperture size results in such a tight focus that it creates a tunneling effect in the photograph for a highly dramatic appearance.
As with most elements of photography, achieving your preferred depth of field is largely a result of taking several shots with experimental settings until you become proficient in anticipating the result.
[See Image 1]