| 摘要 |
<p>A zoom lens system composed of four lens groups, capable of correcting image blurring. The correction is made by moving the entire third lens group in the direction vertical to an optical axis when varying magnification and when focusing, the third lens group being fixed relative to an image surface. The zoom lens system is a system for forming an optical image of an object in a magnification variable manner and has, in the order from the object side to the image side, a first lens group having positive power, a second lens group having negative power, the third lens group including at least one non-spherical surface and having positive power, and a fourth lens group having positive power. To change the magnification of an optical image, the first lens group and the third lens group are fixed relative to the image surface in the direction of the optical axis, while the second lens group and the fourth lens group are movable in the direction of the optical axis. In adjusting the focus of the optical image, the fourth lens group is movable in the direction of the optical axis, and in correcting optical image blurring produced by vibration of the zoom lens system, the third lens group is movable in the direction perpendicular to the optical axis. Further, the zoom lens system satisfies specific conditions.</p> |
