Patent ID: 7920340
Filing Date: 2011-04-05
Classification: G02B

Abstract:
1. An optical lens system for taking image comprising, in order from the object side to the image side: an aperture stop; a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a fourth lens element with negative refractive power having a concave image-side surface; and in the optical lens system for taking image, the number of lens elements with refractive power being limited to four; wherein a distance from the aperture stop of the optical lens system for taking image to an image plane is DT, a maximum image height of the optical lens system for taking image is ImgH, they satisfy the relation: an object to be photographed is imaged on an electronic imaging sensor, a focal length of the optical lens system for taking image is f, a radius of curvature of the object-side surface of the first lens element is R