| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which has high zoom ratio, is excellent in lens diameter reduction and weight reduction, and is suitable for a three-imager pick-up system. SOLUTION: The zoom lens has four lens groups which are, in order from the object side: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; a third lens group G3 having positive refractive power; and a fourth lens group G4 having positive refractive power. When a lens position changes from a wide angle edge to a telephoto edge, the second lens group moves toward the image side, the fourth lens group moves so as to compensate for an image-side change caused by the movement of the second lens group, the first lens group and the third lens group are fixed in the direction of an optical axis, and an aperture diaphragm S is disposed on the object side of the third lens group. The third lens group is composed of a negative part group L31 having negative refractive power; and a positive part group L32 interspatially disposed on the image side of the negative part group. An image is shifted by shifting the positive part group in a direction perpendicular to the optical axis. COPYRIGHT: (C)2007,JPO&INPIT
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