Patent ID: 7508592
Filing Date: 2009-03-24
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object side toward an image side: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; a fourth lens group having positive refractive power; and a fifth lens group having positive refractive power; upon zooming from a wide-angle end state to a telephoto end state, the first lens group moving at first toward the image side and then toward the object side, a distance between the first lens group and the second lens group decreasing, a distance between the second lens group and the third lens group increasing, a distance between the third lens group and the fourth lens group decreasing, and a distance between the fourth lens group and the fifth lens group increasing, wherein the following conditional expression is satisfied: where fw denotes a focal length of the zoom lens system in the wide-angle end state, and S45w denotes a position of the primary principal point of the fifth lens group measured along the optical axis from the secondary principal point of the fourth lens group.