Hyperfocal is the most intuitive and fastest focusing system in the world. In short, focusing from the foreground to infinity. Hyperfocal is the characteristic of lenses that have a considerable depth of field; generally these are so-called "fixed focus" lenses like those existing in cheap pocket cameras but also in smartphones and iPads.
In professional photography, however, they are a peculiar characteristic of so-called wide-angle lenses between 21 mm and 35 mm, lenses which have the advantage of not producing distortions and vignetting in the photos.
If we look at one of these lenses we observe the following rings placed on the lens: aperture scales; distance scales; depth of field scales. Now if we set the aperture to a value, for example aperture 11, we will see that in the depth of field scale engraved on the lens we will find the indication 11 of the set aperture twice. Corresponding to the depth of field scale, engraved on the lens, we will find, coinciding with the value 11, on the right, the value for example 1.2, while coinciding with the value 11 on the left we will find the infinity symbol.
This means that all objects from 1.2 m to infinity are exactly in focus. But what is hyperfocal? Technically it is the focusing distance that allows the greatest possible depth of field, considering the relationship between the focal length of the lens used and the aperture at which it is set.
But what is the trick to exploiting the advantages of hyperfocal?
In practice, we position the infinite value of the distances on our focusing ring on the lens in correspondence with the aperture that we want to set and observe the value in correspondence with the same aperture value in the depth of field scale. In fact, it will be observed that the more closed the diaphragm the greater the depth of field range will be, and the more the diaphragm opens the smaller the depth of field will be. Once the hyperfocal has been calculated in this way by acting on the diaphragm ring of the lens, a shutter speed is set, based on the ISO sensitivity set for correct exposure.
For example, working in aperture priority, once the ISO sensitivity has been set, the shutter speed can be set automatically and the camera will select the optimal shutter speed based on the ISO sensitivity and the aperture set. In this case everything will be perfectly in focus and all that remains is to concentrate only on the composition of the photograph you want to take.