| 摘要 |
A focusing method for an optical instrument for magnified viewing of an object is disclosed. The instrument includes instrument optics, an adjusting unit for adjusting the focal position when viewing the object by means of the instrument optics, as well as a recording unit which records the object by means of the instrument optics. The method includes: a) producing at least two images with different focal positions, b) applying several different sharpness functions each of which has an absolute extremum which specifies the optimum focal position to be set for the viewing and which lies in a close focus range of the sharpness function adjoined on both sides by a far focus range which is more susceptible to interferences during recording than the close focus range and therefore contains local secondary extrema, in each case to each of the at least two images, and evaluation thereof with the focal position as a variable such that a sharpness function variation direction of the focal position is calculated for each sharpness function in order to arrive at the optimum focal position, c) determining a main variation direction based on all sharpness function variation directions, and d) using the determined main variation direction during further focusing. |
