Patent attributes
A compact, low-profile, low-cost imaging lens with an F-value of 2.5 or less and a wide field of view which corrects aberrations properly. Its elements are arranged from an object side to an image side: a first positive optical element group including a first positive lens having a convex object-side surface, a second negative lens having a concave image-side surface, and a third positive lens having a convex object-side surface; a second positive optical element group including a fourth positive lens having a convex image-side surface; and a third negative optical element group including a fifth negative double-sided aspheric lens having a concave image-side surface. The fifth lens image-side surface has at least one pole-change point off an optical axis. A double-sided aspheric aberration correction optical element with virtually no refractive power is located in an air gap nearer to the image plane than the first optical element group.
