Patent ID: 6498902
Filing Date: 2002-12-24
Classification: G02B

Abstract:
A finder indication optical system in which an indication device is provided in the vicinity of an image surface of an objective optical system or provided in a position in which the diopter is substantially equivalent to the image surface of the objective optical system when viewed through a finder field of view of a finder optical system, so that photographing information formed by the indication device can be viewed outside of the photographing area which is formed to be seen in the finder field of view , said indication optical system comprising:a correction surface which is provided along a light path of the finder indication optical system to correct an astigmatic difference thereof, wherein the correction surface is provided at a predetermined position from the optical axis of the finder optical system as the origin point, and wherein the correction surface is formed in the following manner: the optical axis defines an X-axis; the direction parallel to the transverse direction of said correction surface and perpendicular to the X-axis, defines a Y-axis; the direction parallel to the longitudinal direction of said correction surface and perpendicular to the X-axis, defines a Z-axis; the coordinates of the center of said correction surface are (&agr;,&bgr;); and the absolute value of curvature C in a section parallel with a plane defined by said X-axis and said Z-axis, at the coordinates (y, z) of the correction surface, is |Cz(y, Z)|; wherein said correction surface is formed so that the absolute value |CZ(y, z)| of the curvature C increases as the absolute value of z at y=&agr; increases.