| 摘要 |
PROBLEM TO BE SOLVED: To provide a high performance zoom lens system for a large diameter standard zoom lens whose open F-number is about 2.8 at the wide angle end and varies during zooming, achieving a sufficient reduction in size while having a vibration-proof mechanism and an inner focus mechanism, and achieving a reduction in the shortest photographic distance.SOLUTION: The zoom lens system includes, in order from the object side to the image plane side: a first lens group G1 having a positive refractive power; a second lens group G2 having a negative refractive power; a third lens group G3 having a positive refractive power; and a fourth lens group G4 having a positive refractive power. The third lens group comprises a third-A lens group G3A having a positive refractive power, and a third-B lens group G3B having a negative or positive refractive power. When zooming from the wide angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the fourth lens group decreases. A part of or the whole of the third-B lens group serves as a vibration-proof lens. |
