Patent ID: 8462444

Claim:
A zoom lens comprising, in a sequence from an object side to an image plane side: a first lens group having a negative refractive power; a second lens group having a positive refractive power; a third lens group having a negative refractive power; and a fourth lens group having a positive refractive power, wherein: during zooming from a wide angle position to a telephoto position, an interval between the first lens group and the second lens group decreases, an interval between the second lens group and the third lens group increases, and an interval between the third lens group and the fourth lens group decreases; when the location of an object changes from ∞ to a close location, the first lens group is moved toward the object to perform focusing; and the zoom lens satisfies the following expression: L W f W · f T ≤ 3.0 where L W , f W , and f T denote an optical overall length at the wide angle position, an overall focal length at the wide angle position, and an overall focal length at the telephoto position, respectively.