Patent ID: 7646552

Claim:
A subminiature imaging optical system comprising: a first lens having positive refractive power and both convex surfaces; a second lens having negative refractive power and a concave image-side surface; a third lens having negative refractive power and a meniscus shape with a convex image-side surface; and a fourth lens having negative refractive power, wherein the first lens has refractive power satisfying following condition 1 and has a dimension in an optical direction satisfying following condition 2, 0.5<f1/f<0.7 condition 1, 1.0<TL/f<1.3 condition 2, where f 1 is a focal length of the first lens, f is an effective focal length of an overall optical system and TL is a distance from an object-side surface of the first lens to an image plane.