Patent ID: 9025255
Filing Date: 2015-05-05
Classification: G02B

Abstract:
1. A zoom lens, substantially consisting of: a first lens group having a positive refractive power, which is fixed while changing magnification; a second lens group having a negative refractive power, which moves from an object side to an image side while changing magnification from a wide angle end to a telephoto end; a third lens group having a negative refractive power, which corrects movement of an imaging surface while changing magnification; and a fourth lens group having a positive refractive power, which is fixed while changing magnification, provided in this order from the object side; the first lens group substantially consisting of: an 11 lens group having a negative refractive power, which is fixed during focusing operations; a 12 lens group having a positive refractive power, which moves during focusing operations; and a 13 lens group having a positive refractive power, which is fixed during focusing operations, provided in this order from the object side; the 11 lens group substantially consisting of: a negative meniscus lens having a concave surface toward the image side; a negative meniscus lens having a concave surface toward the image side; and a cemented lens constituted by a biconcave lens toward the object side and a biconvex lens toward the image side which are cemented together, provided in this order from the object side; the second negative meniscus lens from the object side and the cemented lens within the 11 lens group satisfying the following conditional formula: wherein D4 is the distance between the surfaces of the second negative meniscus lens and the cemented lens, and f1 is the focal length of the first lens group.