Patent ID: 6091903
Filing Date: 2000-07-18
Classification: G02B

Abstract:
A macro lens system of which a focusing state is adjustable between an infinite focusing state where said macro lens system focuses on an object at infinity and a close focusing state where said macro lens system focuses on an object at the minimum object distance, said macro lens system comprising:a focusing lens group that moves along an optical axis between an infinite focusing position which is close to an image plane and a close focusing position which is far from said image plane;an aperture whose full-opening diameter is changeable; anda controller that controls said aperture so that said full-opening diameter increases in response to movement of said focusing lens group toward the object side;wherein the following conditions (1) and (2) are satisfied:0.5<Fe/{F(1-Mc)}<0.9 (1);andFe<7 (2);wherein,F is an effective F-number at the infinite focusing state;Fe is an effective F-number at the close focusing state; andMc is a lateral magnification at the close focusing state.