Patent ID: 8120850

Claim:
A zoom lens system, in order from an object side to an image side, comprising: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and a fourth lens unit having positive optical power and being arranged closest to the image side, wherein at the time of zooming, at least the first lens unit moves from a wide-angle limit to a telephoto limit, the fourth lens unit includes a first sub lens unit having positive optical power and a second sub lens unit having negative optical power, the second sub lens unit being arranged at the image side relative to the first sub lens unit, at the time of compensating image blur caused by vibration applied to the zoom lens system, the first sub lens unit or the second sub lens unit moves in a direction perpendicular to the optical axis, and the following condition is satisfied: 0.5 <δ t 1 /f 1 <1.1 (9) where, δt l is an amount of movement of the first lens unit from a wide-angle limit to a telephoto limit (where, the position of the wide-angle limit is set as a reference, and expansion to the object side from the reference position is regarded as a positive value), and f l is a focal length of the first lens unit.