Patent ID: 7196853

Claim:
A zoom lens system comprising, in order from an object side to an image side: a first lens unit having a positive optical power; a second lens unit having a negative optical power; and a rear lens group having a positive optical power as a whole in an entire zoom range, the rear lens group having a plurality of lens units which move during zooming, wherein the plurality of lens units contains a lens component having a negative optical power, whose interval from the lens unit disposed adjacent to the component changes during the zooming, the lens component of the negative optical power consists of: a front lens sub-component of a negative optical power; and a rear lens sub-component of a negative optical power, wherein at least one of a part of the front lens sub-component and the rear lens sub-component is moved in such a manner as to have a component in a vertical direction with respect to an optical axis, thereby displacing an image formed by the zoom lens system, wherein assuming that a focal length in a wide angle end of the whole zoom lens system is Fw, and a focal length in a telephoto end of the whole zoom lens system is Ft, a focal length Fm can be defined as: Fm =√{square root over (( Fw·Ft ))}, and where a focal length of the first lens unit is F 1 , a focal length of the second lens unit is F 2 , a focal length of the lens component having the negative optical power is FN, and the focal length of the rear lens group in a zoom position of the focal length Fm is F 3 m, wherein the following conditions are satisfied: 1.2 <F 1/ Fm< 2.5; 0.2<| F 2/ Fm|< 0.4; 0.4<| FN/Fm|< 1.2; and 0.6< F 3 m/Fm< 1.2.