Patent ID: 8023814

Claim:
A zoom lens system comprising a plurality of lens units and an aperture diaphragm arranged in the lens units, and performing zooming by changing intervals among the lens units, wherein the plurality of lens units, in order from an object side to an image side, includes: 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, the aperture diaphragm is arranged on the object side relative to the fourth lens unit so as to be adjacent to the fourth lens unit, the fourth lens unit includes, in order from the object side to the image side, a lens element having positive optical power, a lens element having positive optical power, and a lens element having negative optical power, and at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, only the third lens unit moves along an optical axis.