Patent ID: 8339717

Claim:
An optical lens comprising; a lens group; and a diaphragm, wherein said lens group comprising a first lens, a second lens and a third lens arranged sequentially, and said diaphragm is positioned in front of said first lens of the said lens group; wherein the lens group forms a negative-positive-positive separated focal power system, in which said first lens is a negative meniscus lens, said second lens is a positive meniscus lens, and said third lens is a positive meniscus lens, all curved surfaces of said first lens, said second lens and said third lens are bent in a direction away from said diaphragm, and the focal length of the lens group is f, the focal lengths of the first, the second and the third lens are respectively f 1 , f 2 , and f 3 , and ratios between the focal length f 1 , f 2 and f 3 and the focal length f of the lens group satisfy the following requirement: −0.7 <f 1 /f<− 0.4 0.9 <f 2 /f< 1.1 0.7 <f 3 /f< 0.9.