| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system which can excellently maintain optical performance even when controlling a vibration, reduce the burden of a vibration-proof mechanism when controlling the vibration, and easily control the vibration.SOLUTION: The optical system comprises a front lens group arranged on the most object side, an intermediate lens group arranged to be adjacent to the image side of the front lens group, and a last lens group arranged to be adjacent to the image side of the intermediate lens group. The intermediate lens group comprises a vibration-proof lens group moved in a direction having a component in a direction vertical to an optical axis, to move an image forming position in the direction vertical to the optical axis and an auxiliary lens group arranged to be adjacent to the vibration-proof lens group and having refractive power having a sign different from that of the vibration-proof lens group. The auxiliary lens group comprises a single lens or a cemented lens, a lens surface on the most object side of the last lens group is strongly concave, and a lens surface on the most image side of the last lens group is convex. A focal length fis of the vibration-proof lens group and a focal length fc of the auxiliary lens group are properly set respectively. |
