Patent ID: 7298561

Claim:
An optical device having a front group formed of a plurality of lenses and a rear group formed of a plurality of lenses, which are arranged from an object side, wherein: the front group includes a negative first lens as a meniscus lens being convex at the object side, and a negative second lens having a stronger curvature at an image side than at the object side, which are arranged in order from the object side, and the first lens is a glass lens and the second lens is a plastic aspherical lens; the rear group includes a positive biconvex third lens, an aperture stop, and a composite lens formed by combining a negative fourth lens with stronger curvature at the image side than at the object side, and a positive biconvex fifth lens in tight contact therewith; and satisfying the following conditions for (C1) and (C2): −2.4 <fI/f<− 1.55 (C1) 0.15 <f 2 /f 1<0.35 (C2) where f denotes a focal distance of a whole system, f1 denotes a focal distance of the first lens, f2 denotes a focal distance of the second lens and fI denotes a focal distance of the front group.