Hyperfocal distance

As hyperfocal distance or hyperfocal distance that finite object distance is used in photography, in which, if you just focused at this distance, objects lying at infinity are also just mapped with acceptable blur. The entire area imaged with acceptable blur, the so-called depth of field, then ranges from half the hyperfocal distance to infinity.

The hyperfocal distance is obtained according to the formula of the focal length and aperture of the lens used and the tolerable circle of confusion diameter, which in turn depends on the film or sensor format used below. The following applies:

  • : Hyperfocal distance measured from the object-side principal plane
  • : Focal length (not the small -screen equivalent of the focal length)
  • : F-number f / 2.8 →
  • : Circle of confusion diameter

The on lenses encountered with fixed focal length of field scales are usually calculated according to this same formula, using as tolerable circle of confusion diameter nowadays usually an empirical estimate of 1/1500 (previously 1/1000) of the image diagonal indicating so at 35 -mm screen Photography about 30 microns, at 6 cm × 6 cm medium format about 50 microns, and so on.

In digital photography, however, is used as the tolerable circle of confusion diameter with color illustrations usually twice, with monochrome illustrations, the simple pixel size of the image sensor. For particularly high-resolution image sensors with large pixel density arise by - especially with monochrome images - often considerably more pixels on the screen diagonal and therefore much smaller circle of confusion diameter than specified above.

Examples

  • Small image, 12 mm lens, aperture f/22 → = 0.23 m
  • Small image, 18 mm lens, aperture f/16 → = 0.69 m
  • Small image, 50mm lens, f/11 → = 7.6 m
  • Small image, 135 mm lens, f / 8 → = 76 m
  • Small image, 400 mm lens, aperture f / 7.1 = 750 → m
  • Small image 1200 mm lens, aperture f / 5,6 → = 8600 m
  • CCD sensor (1/2, 5 "), 6 mm lens, aperture f / 2,8 → = 3.02 m
  • CCD sensor (1/2, 5 " ), 60 mm lens, aperture f / 4.3 = 196 → m

In practice, the hyperfocal distance is a rough guideline, since focusing errors blur not abruptly begins, but slowly increases. A landscape shot with Hyperfokaleinstellung produced a recording with borderline sharpness of the entire main motif. In many shots high sharpness of the main subject is more important than a moderate sharpness of the entire image.

On the distance scale of the lens object distance is specified in the rule. The hyperfocal distance can not be readily derived from the above- mentioned law. A focused at infinity has nothing to do with the hyperfocal distance. With most lenses, the sharpness setting goes even beyond infinity to be not trigger the auto focus in auto focus.

Cardinal point (optics)#Principal planes and points Medium format (film)
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