Patent ID: 8189272

Claim:
An optical lens assembly for image taking, sequentially from an object side to an image side along an optical axis, comprising: a first lens element with refractive power; a second lens element with positive refractive power, being bi-convex; a third lens element with negative refractive power, having a concave object-side surface and a convex image-side surface, and at least one of the object-side and image-side surfaces of the third lens element being aspheric; and a fourth lens element with positive refractive power, having a convex object-side surface and a concave image-side surface, and at least one of the object-side surface and the image-side surface having at least one inflection point; wherein f is a focal length of the optical lens assembly for image taking, f 2 is a focal length of the second lens element, f 3 is a focal length of the third lens element, f 4 is a focal length of the fourth lens element, R 3 is a curvature radius of the object-side surface of the second lens element, R 4 is a curvature radius of the image-side surface of the second lens element, and R 8 is a curvature radius of the image-side surface of the fourth lens element; and the following conditions are satisfied: 0 <f/f 4 <0.75; −1.0<( R 3 +R 4 )/( R 3 −R 4 )<0.8; 0 <R 8 /f< 1.0; 1.2 <|f/f 2 |+|f/f 3 |<3.1.