Patent ID: 8218243
Filing Date: 2012-07-10
Classification: G02B

Abstract:
1. A zoom lens comprising: a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power, in order from an object side to an image side; an aperture stop that determines an F-number disposed on the object side of the second lens unit, to adjust light amount; a secondary aperture having a constant aperture diameter disposed on the image side of the second lens unit, wherein all the first lens unit, the second lens unit, and the third lens unit move during zooming, wherein the second lens unit includes lens components having a positive refractive powers disposed at a position closest to the object side and a position closest to the image side, and wherein the following condition is satisfied: where dd denotes a distance on an optical axis between a lens surface closest to the image side in the second lens unit and the secondary aperture, and fw denotes a focal length of the entire zoom lens at a wide angle end.