Patent ID: 7436604

Claim:
An optical lens system for taking image comprising two lens elements with refractive power and an aperture stop, from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface of the first lens element being aspheric; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface, the object-side surface and the image-side surface of the second lens element being aspheric, the image-side surface of the second lens element being formed with an inflection point; and the aperture stop located in front of the first lens element; wherein a focal length of the second lens element is f 2 , a focal length of the optical lens system is f, an entrance pupil diameter is EPD and they satisfy the relation: −0.55 <f/f 2<−0.05 f /EPD<3.6.