US Patent 7365912 Compact zoom lens

A compact zoom lens suitable for an imaging optical system using a solid-state image sensing device is provided. The zoom lens includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The first through third lens groups are sequentially arranged from an object side toward an image side. The first, second, and third lens groups move when magnification changes from the wide-angle position to the telephoto position, and a refractive index G1n of at least one lens element included in the first lens group satisfies 1.90<G1n<2.00.