| 摘要 |
Provided is an endoscope objective optical system having a small diameter, a wide angle of view in water, a small variation in the angle of view, and a short overall length. The endoscope objective optical system includes, in the order from an object side, a front group GF having a negative refractive power, an aperture diaphragm S, and a rear group GR having a positive refractive power. The front group includes a first negative lens L1 and a second negative lens L2. The endoscope objective optical system satisfies the following conditional expressions (1), (2), (3), and (4): 1 < Iw/ft < 1.8 (1) 4 < Lt/Iw < 9.5 (2) Lsf/ft < 2.8 (3) 0.38 < ∑La/Lsf < 0.6 (4) |
