Patent ID: 8358471
Filing Date: 2013-01-22
Classification: G02B

Abstract:
1. A zoom lens comprising: sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, wherein the zoom lens is configured so that when the zoom lens is zoomed from a wide angle position to a telephoto position, all of the first lens group, the second lens group, the third lens group, and the fourth lens group move relative to one another so that a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group reduces, and a distance between the third lens group and the fourth lens group increases, wherein the first lens group comprises a negative lens and a positive lens, the negative lens and the positive lens of the first lens group comprises a doublet lens, wherein the zoom lens satisfies the following expressions: wherein nd1n denotes a refractive index with respect to a line d of the negative lens of the first lens group, nd1p denotes a refractive index with respect to the line d of the positive lens included in the first lens group, vd1n denotes an Abbe number of the negative lens of the first lens group, and vd1p denotes an Abbe number with respect to the line d of the positive lens of the first lens group, wherein the third lens group moves perpendicularly to an optical axis to compensate for a hand shake, and wherein the zoom lens satisfies the following expression: wherein f2 denotes a focal length of the second lens group, f3 denotes a focal length of the third lens group, and fw denotes a total focal length at a wide angle position, and wherein the zoom lens satisfies the following expression: wherein D3t denotes an air gap distance between the first lens group and the second lens group on an optical axis at a telephoto position, and Lt denotes a distance from the vertex of the lens closest to an object side of the first lens group at a telephoto position to an image plane on the optical axis.