Archived posting to the Leica Users Group, 1999/06/18

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
Subject: [Leica] Depth of Field calculations
From: "Richard J. Wyble" <rwyble@erols.com>
Date: Fri, 18 Jun 1999 08:27:43 -0400 (EDT)
 
Several days ago a depth-of-field discussion developed around the
Tri-Elmar which evidently has no depth of field scales on the lens. For
those inclined to futz about with such things, here is a formula which
should serve well, courtesy of Carl Shipman. Note that the "FF" is my
ignorant way of not knowing just how to write "F squared" in ASCII
notation. This should work reasonably well for 'normal' lenses.


Near Limit =  FFS
              --------
              FF + SfC

Far Limit  =  FFS
              ---------
              FF - SfC

Depth of Field
           =  (Far Limit) - (Near Limit)

C = diameter of circle of confusion in meters (e.g., 0.033mm = 0.000033m)
f = lens aperature setting or f-number
S = distance to subject in meters
F = lens focal length in meters
Depth of Field is calculated in meters.
For those who want conversions to feet, multiply meters by 3.3

  rwyble@erols.com
  Richard J. Wyble