Patent ID: 7274519
Filing Date: 2007-09-25
Classification: G02B

Abstract:
1. A zoom lens system having only three lens groups, including, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; and a third 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, at least the first lens group and the third lens group are moved along the optical axis toward the object, and the following conditional expression is satisfied: where f1 denotes a focal length of the first lens group, and fw denotes a focal length of the zoom lens system in the wide-angle end state, wherein the first lens group includes, in order from the object, a cemented positive lens constructed by a negative meniscus lens cemented with a positive lens, and a single positive lens having positive refractive power.