Patent ID: 6788474
Filing Date: 2004-09-07
Classification: G02B

Abstract:
A zoom image pickup optical system comprising in order from an object side:a first lens unit having positive refractive power; a second lens unit having negative refractive power; a stop; a third lens unit having positive refractive power; and a fourth lens unit having positive refractive power, wherein at least the second lens unit is moved along an optical axis to change a magnification, wherein at least one of the third lens unit and the fourth lens unit is moved along the optical axis to change the magnification, wherein an air space between the first lens unit and the second lens unit is changed during a magnification change, wherein the stop is kept stationary during the magnification change, wherein a space between the third lens unit and the fourth lens unit is changed during the magnification change, wherein said first lens unit comprises, in order from the object side, a cemented lens component and one lens component, wherein said third lens unit consists of, in order from the object side, a single positive lens element having at least one aspherical surface on the object side of the single lens element and a menisucus cemented lens component convex to the object side wherein said fourth lens unit consists of one positive lens component having at least one aspherical surface on an image side of the positive lens component, and wherein said zoom image pickup optical system has a zoom ratio of 5 of higher.