Patent ID: 6333822
Filing Date: 2001-12-25
Classification: G02B

Abstract:
A variable focal length lens system comprising, in order from an object side:a first lens group;a second lens group; anda third lens group;whereinwhen a lens group positions are changed from a wide-angle end state which gives the shortest focal length to a telephoto end state which gives the longest focal length, each lens group is moved through the followings states in the following order:a state focused at infinity in the wide-angle end state,a state focused at near object in the wide-angle end state,a state focused at infinity in an n-th focal length state (n=2, 3, 4, . . . ),a state focused at near object in the n-th focal length state,a state focused at infinity in the telephoto end state, anda state focused at near object in the telephoto end state; andwhereinthe second lens group has an aperture diaphragm, and lens elements are arranged to both object and image sides of the aperture diaphragm;when the lens group positions are changed from the wide-angle end state to the telephoto end state,the first and second lens groups are moved such that a moving ratio of the first lens group to the second lens group is always same; andthe third lens group is moved such that;a space between the second lens group and the third lens group increases when a focusing state in a predetermined focal length is changed from infinity to near object, andthe space decreases when the focusing state is changed from said state focused at near object to a state focused at infinity in a neighboring focal length state.