LARGE APERTURE RATIO INTERNAL FOCUSING TELEPHOTOGRAPHIC ZOOM LENS

摘要

PPROBLEM TO BE SOLVED: To provide a large aperture ratio internal focusing telephotographic zoom lens by which vibration-proof photography is performed and whose FNO (f-number) is about 4. PSOLUTION: The zoom lens is equipped with a 1st lens group G1 having positive refractive power, a 2nd lens group G2 having negative refractive power, a 3rd lens group G3 having positive refractive power and a 4th lens group G4 having positive refractive power in order from an object side, and performs variable power by moving the lens groups G2 and G3 along an optical axis. The lens group G4 is constituted of a front group G4f having positive refractive power, a middle group G4m having negative refractive power and a rear group G4r having positive refractive power in order from the object side, and performs vibration-proof correction by making the middle group G4m eccentric perpendicularly to the optical axis. The lens group G1 having the positive refractive power is constituted of a front group G1f, a middle group G1m and a rear group G1r, which are respectively fixed, movable and fixed in an optical axis direction with respect to an image surface, and performs short-distance focusing by moving the middle group G1m in the optical axis direction. PCOPYRIGHT: (C)2004,JPO