| 摘要 |
Provided is an optical system for an endoscope, the optical system including a negative lens group G1, an aperture diaphragm S and a positive lens group G2 in this order from an object side, wherein the negative lens group G1 includes a negative first lens L1 and a negative second lens L2 in this order from the object side; and wherein the optical system meets conditional expressions (1) and (2): 0.05 < H 100 × nd �¢ 01 - 1 / Rf �¢ 01 < 0.38 and 0.5 < enp / FL < 2.5
where: H(100) is a height at which a principal ray with an angle of incidence of 100 degrees which falls on a surface of the first lens falls on the surface of the first lens; Rf01 is a curvature radius of an L surface of the first lens; nd01 is a refractive index of the first lens L1; FL is a focal length of an entire system; and enp is an entrance pupil position. |
