Objective lens for endoscope

摘要

An objective lens for an endoscope including a first lens group including one negative lens, a second lens group having a positive power, a third lens group having a negative power, and an aperture stop provided between the first lens group and the second lens group. The objective lens satisfies the relationships:-1.4<f1/f<-0.5,0.55<f2/f<0.85; and f3/f<-2.0,Where f designates a focal length of the entire objective lens; f1 designates a focal length of the first lens group; f2 designates a focal length of the second lens group; and f3 designates a focal length of the third lens group.