Patent ID: 8730587

Claim:
A zoom lens comprising in order from an object side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; and a last lens group having a positive refractive power, wherein at the time of zooming from a wide angle end to a telephoto end, the first lens group is fixed, the second lens group moves toward a side of an image plane, the third lens group is fixed, and the fourth lens group moves, and at the time of focusing, the fourth lens group moves, and the zoom lens satisfies the following conditional expression (101) 0.20<log(β34 T/β 34 W )<0.9·log γ (101) where, β34W denotes a magnification of a combined system of the third lens group and the fourth lens group at the wide angle end, β34T denotes a magnification of the combined system of the third lens group and the fourth lens group at the telephoto end, fW denotes a focal length of the overall zoom lens system at the wide angle end, fT denotes a focal length of the overall zoom lens system at the telephoto end, and γ=fT/fW>7, and each of the magnification or the focal length is a magnification or a focal length at the time of infinite object point focusing.