Patent ID: 7986458

Claim:
A zoom lens system comprising, in order from an object side to an image side: a first lens group having a positive refractive power and being fixed; a second lens group having a negative refractive power and being movable in an optical axis direction to perform at least zooming; a third lens group having a positive refractive power and being fixed; a fourth lens group having a positive refractive power and being movable in the optical axis direction to perform focal position correction and focusing by performing a zooming; and a fifth lens group having a positive refractive power, wherein: the fifth lens group includes, in order from the object side to the image side, a fixed group having a negative refractive power, and a movable group having a positive refractive power and being movable in a direction substantially orthogonal to the optical axis, the fixed group of the fifth lens group is formed by a cemented lens composed of a first lens having a positive refractive power, a second lens having a negative refractive power and a third lens having a negative refractive power cemented together in the order from the object side to the image side, the image formed on an image surface is movable in a direction substantially orthogonal to the optical axis by moving the movable group of the fifth lens group in the direction substantially orthogonal to the optical axis, and the zoom lens system is configured to satisfy the following conditional expressions (1) and (2): 0.6 <|f 51 /f 52|<1.0 (1) 0.2 <fw/f 52<0.5 (2) where f51 is the focal length of the fixed group of the fifth lens group, f52 is the focal length of the movable group of the fifth lens group, and fw is the focal length of the zoom lens system at a wide-angle end.