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Hyperfocal distance is a distance used in optics, especially photography. When a lens is focused at infinity, objects at the hyperfocal distance and beyond are acceptably sharp.

Of more practical interest, the hyperfocal distance is also a very close approximation to the closest distance at which a photographic lens can be focused while keeping objects at infinity acceptably sharp; that is, with the maximum depth of field. When focused at this distance, all objects at distances from half of the focus distance out to infinity will be acceptably sharp. The term hyperfocal distance is often used to refer to this focus distance.

Formulae

The hyperfocal distance is the product of the square of the focal length divided by both the f-stop and the circle of confusion limit chosen.

${\displaystyle H={\frac {F^{2}}{(f)(Cc)}}}$

where

H is hyperfocal distance

F is focal length

f is f-stop

Cc is the circle of confusion limit

The closest focus distance that allows depth of field to extend to infinity is:

${\displaystyle D=H+F\,}$

where

D is the focus distance

H is the hyperfocal distance computed as above

F is focal length

Examples

As an example, let's compute the hyperfocal distance for a 50 mm lens at f/16 using a circle of confusion of 0.02 mm (which might be acceptable for some amount of enlargement). In the formula above, we make F = 50 mm, f = 16, and Cc = 0.02 mm; then we compute H:

${\displaystyle H={\frac {(50{\mbox{ mm}})^{2}}{(16)(0.02{\mbox{ mm}})}}}$

${\displaystyle H={\frac {(50{\mbox{ mm}})(50{\mbox{ mm}})}{(16)(0.02{\mbox{ mm}})}}}$

${\displaystyle H=7812.5{\mbox{ mm}}\,}$

The hyperfocal distance is about 7.8 m. We can then compute D:

${\displaystyle D=7812.5{\mbox{ mm}}+50{\mbox{ mm}}\,}$

${\displaystyle D=7862.5{\mbox{ mm}}\,}$

If we focus the lens at a distance of 7.9 m, then everything from half that distance (4 m) to infinity will be acceptably sharp in our photograph.

Alternate usage

In informal usage, the focus point that allows a particular range of distances to be acceptably in focus at a particular aperture is frequently called the hyperfocal distance. This is an extension of the term to include depth of field ranges that do not extend to infinity.

External links

• http://www.dofmaster.com/dofjs.html to calculate hyperfocal distance and depth of field
• Understanding Hyperfocal Distance and Charts: real-world use for photographers, including its shortcomings and a hyperfocal chart calculator

• Optics
• Length
• Photographic terms