Patent ID: 7251081
Filing Date: 2007-07-31
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object: 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, the first, second, third, and fourth lens groups move along an optical axis and the second lens group moves along a zoom trajectory having a concave shape facing to the object, the fourth lens group being composed of, in order from the object, a front lens group having positive refractive power, and a rear lens group having negative refractive power with an air space in between, and the following conditional expression being satisfied: where f 4 denotes the focal length of the fourth lens group, f 4 F denotes the focal length of the front lens group, and f 4 R denotes the focal length of the rear lens group.