Patent ID: 8836846
Filing Date: 2014-09-16
Classification: G02B

Abstract:
1. A zoom lens comprising: a first lens group having negative power; a second lens group having positive power; a third lens group having negative power; and a fourth lens group having positive power sequentially arranged from an object side toward an image side, wherein when a magnification at a wide angle side is changed to a magnification at a telescopic side, the first lens group is so moved along an optical axis that a distance between the first lens group and the second lens group decreases, and the second lens group, the third lens group, and the fourth lens group are moved from the image side toward the object side, the third lens group is moved along the optical axis for focusing, and the zoom lens satisfies the following conditional expression (1) where f3 represents the focal length of the third lens group, fw represents a focal length of the entire lens system at the wide angle end, and ft represents the focal length of the entire lens system at the telescopic end.