Patent ID: 8125561

Claim:
A zooming optical system having six lens groups comprising in order from an object side: a first lens group having a positive refracting power, which is fixed at the time of zooming; a second lens group having a negative refracting power, which is movable at the time of zooming; a third lens group having a positive refracting power, which is fixed at the time of zooming; a fourth lens group having a positive refracting power, which is movable at the time of zooming; a fifth lens group having a negative refracting power, which is movable at the time of zooming; and a sixth lens group having a positive refracting power, which is fixed at the time of zooming, wherein the first lens group includes a reflecting optical element for folding an optical path, and the third lens group includes an aperture stop, and the fifth lens group includes a single lens, and the zooming optical system satisfies the following conditional expression 0.5 ≦f 1/√( fw·ft )≦2.0 where, f1 denotes a focal length of the first lens group; fw denotes a focal length of the overall zooming optical system at a wide angle end, and ft denotes a focal length of the overall zooming optical system at a telephoto end.