Patent ID: 8982474
Filing Date: 2015-03-17
Classification: G02B

Abstract:
1. A zoom lens, comprising: in order from an object side to an image side along an optical axis, a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a negative refractive power; a fourth lens group having a positive refractive power; a fifth lens group having a positive refractive power; and an aperture stop between the third and fourth lens groups, wherein all of the lens groups are moved such that, in the case of changing a magnification from a wide-angle end to a telephoto end, an interval between the first and second lens groups is increased, an interval between the second and third lens groups is increased, an interval between the third and fourth lens groups is decreased, and an interval between the fourth and fifth lens groups is decreased, the focusing is performed by displacement of the third lens group, the third lens group includes one negative lens, at least one aspheric surface is provided on the object side of the aperture stop and the image side of the aperture stop, and an entire optical length at the telephoto end Lt, a maximum distortion at the wide-angle end Disw, an image height Y′, a focal length of the entire system at the wide-angle end Fw, a focal length of the entire system at the telephoto end Ft, a geometric average of Fw and Ft Fm {=[[√]](Fw×Ft)