Patent ID: 7218456
Filing Date: 2007-05-15
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object along an optical axis: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having positive refractive power; wherein when a state of lens group positions varies from a wide-angle end state to a telephoto end state upon focusing on infinity, the first lens group moves with respect to an image plane, the second lens group moves at first to the image and then to the object, the third lens group moves to the object, the fourth lens group moves to the object, and the fifth lens group moves with respect to the image plane along the optical axis such that a variable distance between the first lens group and the second lens group increases, a variable distance between the second lens group and the third lens group decreases, a variable distance between the third lens group and the fourth lens group decreases, and a variable distance between the fourth lens group and the fifth lens group increases and the following conditional expressions being satisfied: where fW denotes the focal length of the zoom lens system in the wide-angle end state, fT denotes the focal length of the zoom lens system in the telephoto end state, f2 denotes the focal length of the second lens group, D5iW denotes a distance between the most image side lens surface of the fifth lens group and the image plane in the wide-angle end state, and D5iT denotes a distance between the most image side lens surface of the fifth lens group and the image plane in the telephoto end state.