| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable focal distance lens system in which miniaturization and a large variable power ratio are attained. SOLUTION: The system is characterized in that a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, and a positive lens group G4 are successively provided from the side of an object, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the first lens group G1 moves toward the object side so that the distance between the third lens group G3 and the fourth lens group G4 varies, when the positional state of the lenses varies from a wide angle end state to a telephoto end state. An aperture diaphragm S is arranged in the vicinity of the object side of the third lens group G3, the third lens group G3 is composed of three lens elements of a positive lens element L31, a negative lens element L32, and a positive lens element L33 successively from the object side, and a predetermined condition equation is satisfied. COPYRIGHT: (C)2004,JPO&NCIPI
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