Optical system for endoscopes

摘要

In order to facilitate accommodation into a narrow space and enable to reserve an observation range wider than those conventionally available while assuring high reliability and brightness sufficient for practical use, the optical system for endoscopes comprises a stop capable of varying aperture into plural number of shapes and/or sizes, and a lens system arranged in the vicinity of said stop and designed in such a manner that the lens surface portions corresponding to the varied stop apertures and sizes have focal length different from each other. Said optical system is applicable as an objective lens, relay lens and eyepiece.