Patent ID: 6618198
Filing Date: 2003-09-09
Classification: G02B

Abstract:
A variable magnification optical system comprising, in order from an object side to an image side;a first lens unit of negative refractive power; a second lens unit of positive refractive power; a third lens unit of negative refractive power; and a fourth lens unit of positive refractive power, wherein the separation between every successive two of said first to fourth lens units is varied to effect variation of magnification, wherein said third lens unit is so moved as to have directional components perpendicular to an optical axis to compensate for shaking of an image caused by vibration of said variable magnification optical system, wherein said third lens unit moves along the optical axis during variation of magnification, wherein said variable magnification optical system satisfies the following conditions: D1W>D1T D2W2T D3W>D3T 1.53|/f2<2.5 2.14/f2<10 where DiW and DiT are separations between the i-th lens unit and the (i+1)st lens unit at a wide-angle end and at a telephoto end, respectively, and fi is the focal length of the i-th lens unit,wherein said system further comprises an aperture stop disposed on the object side or the image side of said third lens unit, which remains stationary when said third lens unit is moved to compensate for shaking of an image and which integrally moves with said third lens unit during variation of magnification, wherein said third lens unit consists of a positive lens and a negative lens, and said fourth lens unit includes a negative lens and a positive lens, and wherein said first lens unit moves in a locus convex to the image side during variation of magnification from the wide-angle end to the telephoto end.