US Patent 7342730 Zoom lens optical system

A compact zoom lens optical system suitable for use in a camera using a solid state photographing device and providing excellent correction of color aberrations, high zooming ratio, and telecentricity. The zoom lens optical system includes: a first lens group having a positive refractive power, the first lens group including two lenses; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power. The first through fifth lens groups are sequentially arranged from an object side and the first lens group is moved during zooming from a wide angle position to a telephoto position.