Patent ID: 7907354

Claim:
A zoom lens comprising the following lens groups in order from an object side: 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; wherein, upon zooming, at least the first lens group and the fourth lens group move to the object side; wherein the third lens group comprises a negative meniscus lens with a convex surface on an image side and with both side faces thereof being exposed to air, the negative meniscus lens being located nearest to the image side in the third lens group; wherein at least one surface in the third lens group is an aspherical surface; wherein the zoom lens satisfies the condition of the following relation: 1.30< f 3 /f 4<1.85, where f 3 is a focal length of the third lens group and f 4 is a focal length of the fourth lens group; and wherein the third lens group further comprises, in order from the object side: a positive lens with a convex surface on the object side; and a cemented lens consisting of a positive lens with a convex surface on the object side and a negative lens with a concave surface on the image side.