Hyperfocal Distance - Formulae

Formulae

For the first definition,

where

is hyperfocal distance

is focal length

is f-number ( for aperture diameter )

is the circle of confusion limit

For any practical f-number, the focal length is insignificant in comparison with the first term, so that

This formula is exact for the second definition, if is measured from a thin lens, or from the front principal plane of a complex lens; it is also exact for the first definition if is measured from a point that is one focal length in front of the front principal plane. For practical purposes, there is little difference between the first and second definitions.