Patent ID: 7760441

Claim:
A zoom lens comprising, in order from an object side thereof, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, a fourth lens group having positive refracting power, and an aperture stop located on an object side of said third lens group for determining an axial light beam, wherein: at least said first lens group and said third lens group move to implement zooming from a wide-angle end to a telephoto end of the zoom lens, in a state at said telephoto end vs. a state at said wide-angle end, said first lens group, said third lens group and said aperture stop are positioned on the object side, a spacing sandwiched between said first lens group and said second lens group grows wide, a spacing sandwiched between said second lens group and said third lens group becomes narrow, a spacing sandwiched between said third lens group and said fourth lens group grows wide, said first lens group consists of two lenses: one positive lens element and one negative lens element, said second lens group consists of three lenses: one positive lens element and two negative lens elements, said third lens group consists of two lenses: one positive lens element and one negative lens element, said fourth lens group consists of one lens: one positive lens element, said third lens group consists of, in order from the object side, one positive lens element and a negative lens element, said positive lens in said third lens group is a double-convex positive lens having convex surfaces on both sides, and said negative lens in said third lens group is a meniscus lens convex on its object side and concave on its image side.