Patent ID: 6940662

Claim:
A lens system comprising, sequentially from a front side to a rear side: a first lens having negative optical power and a meniscus shape with a convex surface facing an object side; a second lens having positive optical power and a double-convex shape; a third lens having negative optical power and a double-concave shape; a fourth lens having positive optical power; and a fifth lens having positive optical power and a double-convex shape, wherein lenses of said lens system are only said first, said second, said third, said fourth and said fifth lens: and wherein letting D 1,2 be an interval between said first and second lenses, D 2,3 an interval between said second and third lenses, bf be a back focus of the entire system, and f be a focal length of the entire system, three conditions given by 0.6 <D 1,2 /f< 1.0 0.55 <D 2,3 /f< 0.85 0.9< bf/f< 1.1 are satisfied; and wherein the lenses are disposed on an optical axis with intervals therebetween.