| 摘要 |
A zoom lens system for forming an image of an object on a solid state imaging device includes a first lens unit having a positive optical power and being movable in a zooming operation; a second lens unit having a negative optical power; and a third lens unit having a positive optical power. The system satisfies at least one the following conditions: 0.8<M1WM/M1MT<2.5; 0.2<DELTAbeta3/DELTAbeta2<1.0; 0.7<m1/Z<3.0; 1.0<img*R<15.0; 1.0<max(T1, T2, T3)<4; and 4.5<fT/|f12W|<15, where M1WM represents movement amount of first lens unit from shortest focal length condition to middle focal length condition; M1MT represents movement amount of first lens unit from middle focal length condition to longest focal length condition; DELTAbeta2 represents lateral magnification ratio of second lens unit; DELTAbeta3 represents lateral magnification ratio of third lens unit; m1 represents movement amount of first lens unit in zooming operation; Z represents zoom ratio fT/fW; fW is system focal length at shortest focal length condition; fT represents system focal length at longest focal length condition; img represents maximum image height; R represents effective diameter of lens surface which is closest to image side among lens surfaces constituting zoom lens system; Ti is axial thickness of an i-th unit; max(T1, T2, T3) is maximum thickness; and f12W represents a composite focal length of first and second lens units at shortest focal length condition.
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