Hyperfocal Distance

In photography, the hyperfocal distance or hyperfocal distance is the finite object distance at which, if one focuses precisely on this distance , objects lying at infinity are also depicted with an acceptable degree of blurring. The entire area imaged with acceptable blurring, the so-called depth of field , then extends from half the hyperfocal distance to infinity.

The infinity marking of this zoom lens is set to the far (right) aperture curve at the smallest aperture f / 32, so the depth of field extends from about 2.9 meters (left aperture curve) to infinity. The hyperfocal distance can now be read from the thick, middle marking line, here about 5.1 m.

Depth of field calculating disc for a 70-200 mm zoom lens. For the focal lengths 80, 90, 105, 120, 135, 150, 170 and 200 mm, the hyperfocal distance can be determined as an example. At 105 mm and an aperture of f / 22, for example, it is around 16 meters.

The hyperfocal distance results from the focal length and aperture of the lens used and the tolerable diameter of the circle of confusion , which in turn depends on the film or sensor format used. The following applies: ${\displaystyle f}$ ${\displaystyle k}$ ${\displaystyle Z}$

${\displaystyle d_{h}={\frac {f^{2}}{k\cdot Z}}+f}$

• ${\displaystyle d_{h}}$: hyperfocal distance measured from the main plane on the object side
• ${\displaystyle f}$: Focal length ( not the 35mm equivalent of the focal length)
• ${\displaystyle k}$: F- number f / 2.8 → ${\displaystyle k=2{,}8}$
• ${\displaystyle Z}$: Circle of confusion diameter

The sharpness scales that can be found on lenses with a fixed focal length are usually calculated according to this formula, with an empirical estimate of 1/1500 (formerly 1/1000) of the image diagonal as the tolerable diameter of the circle of confusion, i.e. for 35 mm small picture photography approx. 30 µm, with the 6 cm x 6 cm medium format approx. 50 µm and so on.

In digital photography, on the other hand, the tolerable circle of confusion diameter for colored images is usually twice the pixel size of the image sensor , for monochrome images . In the case of particularly high-resolution image sensors with a high pixel density, this often results - in particular in the case of monochrome images - considerably more image points on the image diagonal and thus also significantly smaller circle of confusion diameters than indicated above.

Examples

• Small picture, 12 mm lens, aperture f / 22 → = 0.23 m ${\displaystyle d_{h}}$
• 35mm, 18 mm lens, aperture f / 16 → = 0.69 m ${\displaystyle d_{h}}$
• 35mm, 50 mm lens, aperture f / 11 → = 7.6 m ${\displaystyle d_{h}}$
• 35mm, 135 mm lens, aperture f / 8 → = 76 m ${\displaystyle d_{h}}$
• 35mm, 400 mm lens, aperture f / 7.1 → = 750 m ${\displaystyle d_{h}}$
• 35mm, 1200 mm lens, aperture f / 5.6 → = 8600 m ${\displaystyle d_{h}}$
• CCD sensor (1 / 2.5 "), 6 mm lens, aperture f / 2.8 → = 3.02 m ${\displaystyle d_{h}}$
• CCD sensor (1 / 2.5 "), 60 mm lens, aperture f / 4.3 → = 196 m ${\displaystyle d_{h}}$

In practice, the hyperfocal distance is a rough guideline, since the blurring does not start suddenly in the event of focussing errors, but rather gradually increases. A landscape picture with hyperfocal setting produces a picture with marginal sharpness of the entire main subject. In many shots, a high degree of sharpness of the main subject is more important than a moderate sharpness of the entire picture.

The distance to the object is usually indicated on the distance scales of lenses . The hyperfocal distance cannot easily be derived from the above-mentioned law. A focus on infinity has nothing to do with the hyper focal distance. With most lenses, the focus setting goes beyond infinity in order not to let the autofocus trigger during automatic focusing.

Web links

• Online calculator to determine the depth of field
• Very extensive depth of field calculator with table output, ideal for creating tables for outdoor use