| 摘要 |
This optical system includes an objective optical system (O), a relay optical system (R), and an eyepiece optical system (E), in that order from the object side. The relay optical system is provided with a first lens group (G1) having positive refractive power, a second lens group (G2) having positive refractive power, and a third lens group (G3) having positive refractive power, in that order from the object side. Furthermore, the relay optical system is capable of reforming, with varying degrees of magnification, the image formed by the objective optical system. This optical system is configured such that, when ｜β｜min represents the minimum absolute value of the image-formation magnification of the relay optical system, and fmin represents the shortest focal distance, 0.7 <｜β｜min < 1.4 and 12 (mm) < fmin < 15 (mm) are satisfied. |
