| 摘要 |
PURPOSE:To suppress the generation of distortion aberration and to attain precise focus detection by making at least one lens surface of a condensor lens a non-spherical surface in a device receiving light transmitted through a photographing lens and detecting the focus of the photographing lens. CONSTITUTION:The front lens surface r2 of the condensor lens Lo is made a rotary hyperboloid and its shape is expressed as follows. Firstly, the X coordinate is formed in a direction parallel with a main optical axis X and the y and z coordinates are formed on two directions vertical to the X coordinate. When the original point is set up on the intersected point between the main optical axis and said lens surface r2 and Co is set up the radius 10,862mm. of a paraxial curvature of said lens serface r2, the rotary hyperboloid of said lens surface r2 is expressed by EX<2>+y<2>+z<2>-2X/Co=0...1 and E=-4. The value of the E determines the shape of the lens surface r2, and when E=1, E>0, E=0, and E<0, the shape of the lens surface r2 is a spherical surface, a rotary elliosoid, a rotary parabolic surface, and a rotary hyperboloid respectively. |
