ELECTRONIC ENDOSCOPE

摘要

A channel through which a treatment tool is insertable is provided in an insertion section. An objective optical system with a fixed focal length or a variable focal length is provided at the head section of the insertion section, and an optical image is focused on the light receiving surface of an imaging element. When an objective is located at a close distance from the head section, an image signal with sufficient resolution is obtainable from the imaging element, and in this state, the head side of the treatment tool having less amount of projection from a head opening of the channel can be focused on the light receiving surface of the imaging element. Required resolution can be achieved also for the distant side.