Patent ID: 7532411

Claim:
A high zoom ratio zoom lens system comprising, in order from an object: a first lens group having positive refractive power; a second lens group; a third lens group; and a fourth lens group; the first lens group including, in order from the object, a negative meniscus lens having a convex surface facing the object, a first positive lens having a convex surface facing the object, and a second positive lens, the first lens group and the second lens group being moved along the optical axis upon zooming from a wide-angle end state to a telephoto end state, and the following conditional expression being satisfied: 0.31< FG 1×( Nd 1 −Nd 2)/ FL 3<0.75 where FG 1 denotes a focal length of the first lens group, FL 3 denotes a focal length of the second positive lens, Nd 1 denotes refractive index of the negative meniscus lens at d-line (wavelength λ=587.6nm), and Nd 2 denotes refractive index of the first positive lens at d-line (wavelength λ=587.6 nm).