Patent ID: 7227701
Filing Date: 2007-06-05
Classification: G02B

Abstract:
1. A zoom lens, comprising, in order from an object side to an image side: a first lens unit of negative optical power; a second lens unit of positive optical power; and a third lens unit of positive optical power, wherein a separation between said first lens unit and said second lens unit and a separation between said second lens unit and said third lens unit are varied during zooming, and wherein, during zooming from a wide-angle end to a telephoto end, said first lens unit moves so that its motion comprises (a) moving toward the image side and (b) moving thereafter toward the object side, and said third lens unit moves so that its position is closer to the image side at the telephoto end than at the wide-angle end, and said zoom lens satisfies the following condition: where M 3 is an amount of movement of said third lens unit toward the image side during zooming from the wide-angle end to the telephoto end with an infinitely distant object focused on, and fw is a focal length of said zoom lens at the wide-angle end, wherein said second lens unit comprises a cemented lens consisting of two lens elements cemented together, wherein the number of lens elements in said second lens unit is three or four, and wherein no lens unit is present between said first lens unit and said second lens unit.