Patent ID: 7388717
Filing Date: 2008-06-17
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object: a first lens group having negative refractive power; a second lens group having positive refractive power; and a third lens group having positive refractive power; the first lens group having only two lens elements, including a negative lens element and a positive lens element, not including a cemented lens, the second lens group including at least two positive lens elements and at least one negative lens element, and the third lens group having only one lens element, wherein the second lens group includes at least one aspherical surface and a cemented lens, no aspherical surface exists in the cemented lens of the second lens group, and when the zoom lens system changes from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases, the following conditional expression being satisfied: where TL denotes a distance between the most object side lens surface of the zoom lens system and an image plane, fw denotes a focal length of the zoom lens system in a wide-angle end state, and ft denotes a focal length of the zoom lens system in a telephoto end state.