Method and apparatus for setting the sharpness of an optical imaging system

摘要

A method and an apparatus for setting the sharpness of an optical imaging system by step-by-step adjustment of the distance between a subject and an objective and by evaluating the sharpness values identified for the individual distances. First, the sharpness values (S) for two distances (R) modified proceeding from a prescribed distance (Ro) by a respective step width in both adjustment directions are identified and the best sharpness value is determined by comparing these sharpness values (S) to the sharpness value (So) for the prescribed distance (Ro). Respectively two distance points (R1 through R4) having defined step widths proceeding from the prescribed distance (Ro) are then identified in an allowed range of adjustment (VS) and the appertaining sharpness values (S1 through S4) are identified. After this, straight lines (G1; G2) are placed through respectively two of the sharpness values (S1 through S4) to the left and right of the sharpness value (So), these being the tangents at the function curve (V) of the sharpness values (S) dependent on the distances (R). The intersection of the straight lines (G1; G2) and the distance value (Rmax) belonging to the intersection are then identified, this yielding the maximum sharpness value (Smax).