Patent ID: 9606327
Date: 2017-03-28
CPC Classifications: G02B

Claim:
1. A lens system comprising, in order from an object side to an image side: a first lens element with negative refractive power having an image-side surface being concave in a paraxial region thereof; a second lens element having an object-side surface being convex in a paraxial region thereof; a third lens element having positive refractive power; a fourth lens element having positive refractive power, wherein an object-side surface and an image-side surface of the fourth lens element are both aspheric; a fifth lens element with negative refractive power having an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof, wherein the object-side surface and the image-side surface of the fifth lens element are both aspheric; and a sixth lens element having an image-side surface being concave in a paraxial region thereof, wherein the image-side surface of the sixth lens element has at least one convex shape in an off-axis region thereof, and an object-side surface and the image-side surface of the sixth lens element are both aspheric; wherein the lens system has a total of six lens elements; there is an air gap in a paraxial region between every two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other; at least three of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element are made of plastic material; wherein a focal length of the lens system is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, and the following conditions are satisfied: