In photography there is a term Depth of Field (DOF). It refers to the area of sharp focus in an image. Shooting with wide apertures, like f2.0, will yield a very narrow DOF. In extreme cases a portrait of a person may have the eyes in focus but the person’s ears and hair may be be out of focus. The narrower the aperture, the wider the DOF. Shooting at an aperture of f8 or higher will usually leave most, if not all of the image in focus. In the demo below, the aperture settings can be seen in the lower right corner of the image. Watch how the DOF is very narrow at f2 and widens until everything from the nearest cornstalks to the farthest trees are in focus at f22.

DOF Demo