Patent ID: 7633686
Filing Date: 2009-12-15
Classification: G02B

Abstract:
1. A zoom optical system comprising in the order from an object side: a first lens group having a negative optical power; a second lens group having a positive optical power; a third lens group having a negative optical power; and a fourth lens group having a positive optical power, wherein in zooming from a wide angle end to a telephoto end, at least the second lens group and the third lens group are moved in a state that a moving range of the second lens group is partially overlapped with a moving range of the third lens group, the first lens group is constituted of a negative lens element and a positive lens element, the second lens group is constituted of two or more lens elements, the third lens group is constituted of a negative lens element, and the zoom optical system satisfies the following conditional expressions (1), (2), and (3): where r r f fw is a focal length of an entirety of the optical system at the wide angle end, ft is a focal length of the entirety of the optical system at the telephoto end, and nd