Patent ID: 8218245
Filing Date: 2012-07-10
Classification: G02B

Abstract:
1. A zoom lens comprising, from an object side in the following order: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a third lens group that has a positive refractive power; and a fourth lens group that has a positive refractive power, wherein: when magnification is changed from a wide angle end to a telephoto end, the lens groups each move so as to increase the distance between the first and second lens groups and to decrease the distance between the second and third lens groups and the distance between the third and fourth lens groups; and the following conditional expressions (1) and (2) are satisfied: where fw is the focal length of the entire system of the zoom lens at the wide angle end; f1 is the focal length of the first lens group; Σd3 is the actual distance on an optical axis from the lens surface that is closest to an object to the lens surface that is closest to an image in the third lens group; and Σd4 is the actual distance on an optical axis from the lens surface that is closest to the object to the lens surface that is closest to the image in the fourth lens group.