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Marco Raugei | profile | all galleries >> Technique >> Depth of Field and Hyperfocal tree view | thumbnails | slideshow

Depth of Field and Hyperfocal

First of all, it must be realized that Depth of Field, or the range of focus distances that will appear acceptably sharp on a photograph is not an objective quantity, but depends on a number of assumptions that one is willing to make on things like human eye resolving power, final image size, viewing distance, and maximum acceptable blur (measured by the size of the so-called 'Circle of Confusion').

Furthermore, all else being equal, a 35mm "full-frame" (FX) camera needs to be stopped down one more stop with respect to an APS-C (DX) camera to attain the same DOF with a lens giving an EQUIVALENT field of view.
E.g. in terms of angle of view AND Depth of Field, a 14mm @ f/11 on DX is approximately EQUIVALENT to a 21mm @ f/16 on "full frame" (FX).

For a more complete and scientifically correct explanation of the physics at play, I refer you to a good photography book, or to some of the excellent on-line resources listed among my Links.

The following table summarizes my quick-and-dirty recommendations on the correct HYPERFOCAL distance (i.e., the minimum focus distance that allows to have sharp-looking detail at infinity) for a range of useful focal lengths:

Focal Length (mm) Hyperfocal at f/11 on APS-C
[CoC = 0.015mm]
Hyperfocal at f/16 on "full frame"
[CoC = 0.0225mm]
14 1.2m (4ft) 0.6m (2ft)
18 2.0m (7ft) 0.9m (3ft)
21 2.7m (9ft) 1.2m (4ft)
24 3.5m (12ft) 1.6m (5ft)
28 4.8m (16ft) 2.2m (7ft)