Patent ID: 8917454
Filing Date: 2014-12-23
Classification: G02B

Abstract:
1. A zoom lens, practically comprising: a first lens group having a negative refractive power; and a second lens group having a positive refractive power, provided in this order from an object side; the first lens group moving along a trajectory which is convex toward an image side, the second lens group moving monotonously toward the object side, and an aperture stop moving integrally with the second lens group when changing magnification from a wide angle end to a telephoto end; the first lens group comprising two lenses, a first lens having a negative refractive power and a second lens having a positive refractive power; at least one of the two lenses of the first lens group being a plastic lens; the second lens group comprising three or fewer lenses, of which at least one is a plastic lens; and the zoom lens satisfying the following conditional formulae: wherein f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, fw is the focal length of the entire system at the wide angle end, d2 is the distance between the first lens and the second lens along an optical axis, ft is the focal length of the entire system at the telephoto end, nd2 is the refractive index of the second lens with respect to the d line, and νd2 is the Abbe's number of the second lens with respect to the d line.