Patent ID: 9223119
Filing Date: 2015-12-29
Classification: G02B

Abstract:
1. A zoom lens which changes an interval between adjacent lens units during a zooming operation, the zoom lens comprising: a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, disposed in order from an object side to an image side; and an aperture stop disposed between a lens surface closest to the object side of the second lens unit and a lens surface closest to the object side of the third lens unit, wherein the third lens unit is moved to the image side during a focusing operation from an infinite object to a short distance object, wherein each of the lens units moves during the zooming operation so that the interval between the third lens unit and the fourth lens unit at a telephoto end is larger than that at a wide angle end, wherein the first lens unit is, in order from the object side to the image side, configured by at most two negative lenses and one positive lens, wherein the third lens unit is configured by a single lens or a cemented lens, and wherein the following conditional expressions are met: where f 2 is a focal length of the second lens unit, f 3 is a focal length of the third lens unit, f 4 is a focal length of the fourth lens unit, f 3 Rw is a combined focal length of the third lens unit and the fourth lens unit when focusing on the infinite object at a wide angle end, and fw is a focal length of the zoom lens at the wide angle end.