| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens obtaining good optical performance in the whole area from infinite distance to close range photography as well as having a vibration-proof function.SOLUTION: The zoom lens comprises: a first lens group G1 including a focus lens group G1Y and 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 including vibration-proof lens group G4Y and having positive refractive power, in this order from an object side. In this case, a fixed lens group G1X in a zoom lens system for varying spacing between all groups, when varying power from a wide angle end to a telephoto end, is composed by separating one piece of lens L1 having negative refractive power and one piece of lens L2 having positive refractive power in this order from the object side. Good optical performance is demonstrated by suppressing an occurrence of a negative spherical aberration occurring when coming close up to 1 m by making curvature Cof a lens surface s2 on the imaging side of the lens L1 greater than curvature Cof a lens surface s3 on the object side of the lens L2. |
