Patent ID: 7492526

Claim:
A high-zoom-ratio zoom lens comprising, in order from an object: 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 fourth lens group having positive refractive power, the third lens group including, in order from the object, a first positive lens having a convex surface facing the object, a second positive lens having a convex surface facing the object, a double concave negative lens having an absolute value of a radius of curvature of the image side surface smaller than that of the object side surface, and a third positive lens having a double convex shape, upon varying a focal length from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group varying, a distance between the second lens group and the third lens group varying, and a distance between the third lens group and the fourth lens group varying, and the following conditional expression being satisfied: 1.87<N33<2.20 where N33 denotes refractive index of the negative lens at d-line, in which the wavelength λ=587.6 nm.