Patent ID: 7133215
Filing Date: 2006-11-07
Classification: G02B

Abstract:
1. A varifocal zoom lens comprising: a first lens group having a negative refractive power; a second lens group having a positive refractive power, consisting of a cemented lens component L a third lens group having a positive refractive power and disposed on the image side of the second lens group; wherein at least the first and the second lens group are moved and the second lens group is moved toward the object side so as to decrease an interval between the first and the second lens group, when a lens state is changing from a shortest-focal-length lens state for the largest field angle to a longest-focal-length lens state for the smallest field angle, an aperture stop is disposed between the first and the second lens group,and the following conditions are satisfied: where D s is the length of an air space between the cemented lens component L 21 and the positive lens component L 22 , R 22 a is the radius of curvature of the surface on the object side of the positive lens component L 22 , R 21 b is the radius of curvature of the surface on the image side of the cemented lens component L 21 , and D a is the distance between the aperture stop and the surface on the image side of the cemented lens component L 21 .