Perspective objective optical system includes, in order from the object side, a front lens group GF consisting of a negative lens, and the optical path converting element P, is composed of an aperture stop S, and a rear lens group GR after having positive refractive power, the rear lens group GR, a positive lens L2, the a cemented lens having a positive refractive power and a cemented lens, in order from the object side, is composed of a positive lens L3 and a negative lens L4, the following conditional expression (1), (2), to satisfy the (3) -2.0 F F / f -1.3 (1) 1.7 f R / f 2.7 (2) 0.63 | f F / f R | 0.88 (3) However, f F , the focal length of the front lens group, f R is the focal length of the rear lens group, f is a perspective objective optical system focal length of the entire system,It is
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机译：透视物镜光学系统从物体侧开始依次包括由负透镜构成的前透镜组GF和由孔径光阑S构成的光路转换元件P，以及具有正折射之后的后透镜组GR。从后方开始，后透镜组GR，正透镜L2，具有正折光力的胶合透镜和胶合透镜由物镜L3和负透镜L4从物侧依次构成，其条件如下：表达式（1），（2）满足（3） -2.0 F / f <-1.3（1） 1.7 R / f <2.7（2） 0.63 <| f F / f R | <0.88（3） 然而， f F ，前透镜组的焦距， f R 是后透镜组的焦距， f是整个系统的透视物镜光学系统的焦距，它是
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