Patent ID: 9019621
Filing Date: 2015-04-28
Classification: G02B

Abstract:
1. An objective optical system comprising: an immovable lens group arranged nearest to an object side, the immovable lens group being fixedly positioned in a focusing operation; and a first movable lens group and a second movable lens group, at least one of which moves along an optical axis in a focusing operation, wherein the immovable lens group has, at a position nearest to the object side, a lens component having a negative power, wherein an amount of variation in magnification per unit movement of the first movable lens group is different from an amount of variation in magnification per unit movement of the second movable lens group, and wherein the objective optical system is configured: to allow the first movable lens group to move alone along the optical axis while the second movable lens group is fixedly positioned; and to allow the second movable lens group to move alone along the optical axis while the first movable lens group is fixedly positioned.