Patent ID: 7333273

Claim:
A zoom lens system comprising, in order from an object: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power; wherein upon zooming from a wide-angle end state to a telephoto end state, each lens group moves along an optical axis such that a distance between the first lens group and the second lens group decreases, a distance between the second lens group and the third lens group increases, and the distance between the third lens group and the fourth lens group decreases; and the first lens group includes a negative lens, at least one lens in the negative lens includes an aspherical surface, and the negative lens satisfies the following conditional expressions: 30≦νd1≦71 when 30≦νd1<36, −0.013 ×νd 1+2.083 ≦nd 1≦1.7, when 36≦νd1<41, −0.013 ×νd 1+2.083 ≦nd 1≦−0.004 ×νd 1+1.844, when 41≦νd1<51, −0.004 ×νd 1+1.714 ≦nd 1≦−0.004 ×νd 1+1.844, when 51≦νd1<61, −0.0015 ×νd 1+1.5865 ≦nd 1≦−0.004 ×νd 1+1.844, when 61≦νd1≦71, −0.0015 ×νd 1+1.5865 ≦nd 1≦−0.009 ×νd 1+2.149 where nd1 denotes refractive index of a material of the negative lens in the first lens group at d-line, which has a wavelength λ=587.6 nm, and νd1 denotes Abbe number of a material of the negative lens in the first lens group at d-line, which has a wavelength λ=587.6 nm.