Patent ID: 8054559
Filing Date: 2011-11-08
Classification: G02B

Abstract:
1. A zoom lens comprising: a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, and a fourth lens group having a positive refracting power, which are disposed in order from an object side to an image side; and an aperture stop disposed at an object side of the third lens group, the second lens group including a negative lens, a positive lens, and a negative lens, which are disposed in order from the object side, wherein when changing the magnification of the zoom lens from a wide angle end to a telephoto end, an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups changes; and the following conditions are satisfied: where fl is a focal length of the first lens group, ft is a focal length of the zoom lens at the telephoto end, and νd1ave is an average Abbe number of the first lens group; and where Tpr is a telephoto ratio of an entire length at the telephoto end to the focal length of the zoom lens at the telephoto end, that is, Tpr=(the entire length at the telephoto end)/(the focal length of the zoom lens at the telephoto end).