| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens whose entire system is compact and which has a high zoom ratio, and a bright F-number over the entire zoom range.SOLUTION: The zoom lens includes, in order from the object side to the image side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a rear group, in which the distance between the first lens group and the second lens group is larger in the telephoto end than in the wide angle end, the distance between the second lens group and the third lens group is smaller in the telephoto end than in the wide angle end, and the distance between the third lens group and the rear group is changed. The rear group has positive refractive power over the entire zoom range. An aperture stop is disposed between the lens surface closest to the image side in the second lens group and the lens surface closest to the image side in the third lens group. The third lens group includes, in order from the object side to the image side, a positive lens G31 including an aspherical surface, a positive lens G32 including an aspherical surface, and a negative lens. The refractive index nd31 for the d-line of the material of the positive lens G31, and the Abbe number &ngr;d32 and the partial dispersion ratio &thetas;gF32 of the material of the positive lens G32 are appropriately set, respectively. |
