Zoom lens, optical apparatus equipped with the zoom lens and method for forming an image of an object and varying a focal length

摘要

A zoom lens comprises the following lens groups in the 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; and 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, which is located nearest to the image side.