US Patent 8724239 Optical lens system for image taking

An optical lens system for image taking includes, in order from an object side to an image side, a first lens element with negative refractive power having a concave object-side surface and a concave image-side surface, a second lens element with positive refractive power having a convex image-side surface, and a third lens element with negative refractive power having a concave image-side surface of the third lens element near an optical axis and a convex image-side surface of the third lens element away from the optical axis. Both the object-side surface and the image-side surface of the third lens element are aspheric. The third lens element is made of plastic.