| 摘要 |
PURPOSE:To execute a correction of aberration as well as focusing, by constituting a rear lens group of 3 moving groups, and moving these moving groups in the optical axis direction, changing each interval. CONSTITUTION:The front lens group having a converging action is constituted of the first, second and third groups, and the rear lens group having a diverging action is constituted of the fourth and fifth groups of negative lenses and the sixth group of a positive lens. In case of focusing to a short distance object from an infinity object, the fourth and fifth groups are moved to the image side, and the sixth group is moved to the object side. When moving them, they are moved so that an air gap between each 3 group becomes narrow. In this way, an aberration variation due to movement of the lens is reduced by reducing the extent of movement in case of focusing. Especially, since the lens is moved so that an interval between each 3 moving group becomes small, the aberration becomes more satisfactory. |
