Patent ID: 6515804
Filing Date: 2003-02-04
Classification: G02B

Abstract:
A zoom optical system comprising in order from the object side:a first lens unit having negative refractive power; a second lens unit having positive refractive power; and a third lens unit having positive refractive power, wherein said optical system is configured to change a magnification by moving at least said first lens unit and said second lens unit so as to change an airspace between said first lens unit and said second lens unit and widen an airspace between said second lens unit and said third lens unit, and wherein said second lens unit consists, in order from the object side, of a biconvex lens element and a cemented meniscus lens component having a convex surface on the object side, and satisfies the following conditions (1) and (2); 1.0T<2.2â€ƒâ€ƒ(1) 1.42/fW<2.8â€ƒâ€ƒ(2) wherein a reference symbol &bgr;2T represents a lateral magnification of the second lens unit at the tele position, a reference symbol f2 designates a focal length of the second lens unit and a reference symbol fW denotes a focal length of the zoom optical system as a whole.