This tab is rather similar to the Depth of Field tab. The DoF tab actually calculates the hyperfocal distance as an intermediate result, but in order to keep the DoF tab "clean," we did not display this result there.
The "hyperfocal distance" is the nearest distance that you can focus a given focal length/aperture combination at and still have "infinity" in focus. Practically speaking, this is the deepest possible depth of field for that focal length/aperture combination.
Some people use the hyperfocal distance rule to "prefocus" their lens for a given aperture for snap shooting. For example, if you have a 50mm lens on a 35mm camera, and want to use an f/11 aperture, you could focus your lens at about 6.7m and have everything from about 3.4m to infinity in focus. Theoretically, then, you could snap a picture of anything in this range, and have it acceptably sharp, without fine-tuning the focus.
A more common use of the hyperfocal distance is maximizing the depth of field for a given aperture. This is a common requirement in landscape photography. Since smaller apertures give greater depth of field, but also cause greater image degradation due to diffraction, it is best to choose the largest aperture that will still give an acceptable in-focus field.
The hyperfocal distance is found with the following formula:
where f is the focal length of the lens, A is the aperture value and c is the circle of confusion value.