Patent ID: 8031256
Filing Date: 2011-10-04
Classification: G02B

Abstract:
1. A zoom lens formed by arranging a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from an object side to an image side, wherein at a time of varying power from a wide-angle end to a telephoto end, said first lens group is moved, said second lens group is moved to the object side, and said third lens group is moved to the image side such that an air interval between said first lens group and said second lens group is decreased and such that an air interval between said second lens group and said third lens group is increased, said first lens group is formed by arranging a first lens as a negative lens of a meniscus shape having a convex surface facing the object side, a second lens as a negative lens of a meniscus shape having a convex surface facing the object side, and a third lens as a positive lens in order from the object side to the image side, said second lens group has a cemented lens formed by joining together a positive lens of a biconvex shape and a negative lens of a biconcave shape, and is formed by four lenses, and the zoom lens is formed so as to satisfy a following conditional expression (1) and a following conditional expression (2): where f11 denotes a focal length of the first lens of said first lens group, f12 denotes a focal length of the second lens of said first lens group, D1 denotes thickness on an optical axis of said first lens group, and Dw denotes a total optical length at a wide-angle end.