Abstract: An embodiment of this disclosure provides an optical lens, which includes, in order from an object side to an image-forming side, a first lens with negative refraction power; a second lens with negative refraction power; a third lens with positive refraction power; a fourth lens with positive refraction power; and a fifth lens with negative refraction power; wherein the second lens has an Abbe number vd2, the fifth lens has a refractive index nd5, and 20?vd2?30 and nd5?1.9.

Abstract: An embodiment of this disclosure provides an optical lens, which includes, in order from an object side to an image-forming side, a first lens with negative refraction power; a second lens with negative refraction power; a third lens with positive refraction power; a fourth lens with positive refraction power; and a fifth lens with negative refraction power; wherein the second lens has an Abbe number vd2, the fifth lens has a refractive index nd5, and 20?vd2?30 and nd5?1.9.

Abstract: An embodiment of this invention provides a zoom lens, which comprises a plurality of lens groups in order from an object side to an image-forming side with positive, negative, positive, and positive refractive power respectively. The lens groups comprise a plurality of aspheric lenses and/or free form lenses and a plurality of plastic lenses. The zoom lens satisfies the following equation: DG/fw<3.5 and TTL/fw<15.5, wherein DG denotes the total summation of the thickness of each lens group, fw denotes the focal length of the zoom lens at the wide-angle end, and TTL denotes a total thickness of the zoom lens at the wide-angle end.

Abstract: An embodiment of this invention provides a zoom lens, which comprises, in order from an object side to an image-forming side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. Further, the zoom lens satisfies the following conditions: (1) DG1/fw>0.72; (2) DG2/fw<0.72; and (3) TTL/fw<7.0, wherein fw is the focal length of the optical zoom lens at a wide-angle end, DG1 is the thickness of the first lens group, DG2 is the thickness of the second lens group, and TTL is the total thickness of the zoom lens, i.e., the distance between the object side of the first lens group and an image-forming plane of the zoom lens.

Abstract: An embodiment of this invention provides a zoom lens, which comprises, in order from an object side to an image-forming side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. Further, the zoom lens satisfies the following conditions: (1) DG1/fw>0.72; (2) DG2/fw<0.72; and (3) TTL/fw<7.0, wherein fw is the focal length of the optical zoom lens at a wide-angle end, DG1 is the thickness of the first lens group, DG2 is the thickness of the second lens group, and TTL is the total thickness of the zoom lens, i.e., the distance between the object side of the first lens group and an image-forming plane of the zoom lens.

Abstract: A fixed-focus lens including a first lens group and a second lens group is provided. The first lens group has a negative refractive power, and consists essentially of a first lens, a second lens, a third lens, and a fourth lens arranged in sequence from an object side to an image side. Refractive powers of the first, second, third, and fourth lenses are negative, negative, positive, and negative respectively. The second lens group is disposed between the first lens group and the image side, and has a positive refractive power. The second lens group includes a fifth lens and a sixth lens arranged in sequence from the object side to the image side. Refractive powers of the fifth lens and the sixth lens are both positive.

Abstract: A fixed-focus lens including a first lens group and a second lens group is provided. The first lens group has a negative refractive power, and consists essentially of a first lens, a second lens, a third lens, and a fourth lens arranged in sequence from an object side to an image side. Refractive powers of the first, second, third, and fourth lenses are negative, negative, positive, and negative respectively. The second lens group is disposed between the first lens group and the image side, and has a positive refractive power. The second lens group includes a fifth lens and a sixth lens arranged in sequence from the object side to the image side. Refractive powers of the fifth lens and the sixth lens are both positive.