Patent ID: 7079328

Claim:
A zoom optical system comprising, in order from an object side: a first lens unit with negative refracting power; a second lens unit with positive refracting power; and another lens unit with negative refracting power, wherein when a magnification of the zoom optical system is changed in a range from a wide-angle position to a telephoto position, at least the second lens unit is moved along an optical axis, wherein the first lens unit includes a path-bending element for bending an optical path, and wherein the zoom optical system satisfies the following condition: −5< f 1/√( fW×fT )<−0.2 where f 1 is a focal length of the first lens unit, fW is a focal length of an entire system under a condition where an infinite object point is in focus at the wide-angle position, and fT is a focal length of the entire system under a condition where the infinite object point is in focus at the telephoto position.