Patent ID: 8602979

Claim:
An electronic endoscope having an insert section to be inserted into a subject, comprising: a cutaway portion included in a distal portion of the insert section, the cutaway portion including a first surface formed from a distal end surface of the distal portion in parallel to a central axis of the insert section and having a part of an outer circumferential surface of the distal portion cut away, and a second surface inclined with respect to the central axis and connected to the first surface; a front-viewing capturing optical system, provided to be exposed from the distal end surface, for transmitting a first incident light in a front-viewing direction in parallel to the central axis; a front lighting optical system, provided to be exposed from the distal end surface, for applying a first illumination light to a first target observed with the front-viewing capturing optical system; an image sensor for capturing an image of a first transmitted light from the front-viewing capturing optical system; a side-viewing capturing optical system, provided to be exposed from the first surface, for transmitting a second incident light in a side-viewing direction orthogonal to the central axis; an optical path changer for reflecting a second transmitted light from the side-viewing capturing optical system towards the image sensor, and for transmitting the first transmitted light to the image sensor; a side lighting optical system, provided to be exposed from the second surface, for applying a second illumination light to a second target observed with the side-viewing capturing system; a forceps outlet provided to be exposed from the second surface, a medical instrument being projected and retracted from the forceps outlet; a focal length changer for changing a focal length of the side-viewing capturing optical system between a focal length for normal observation and a focal length for magnifying observation, wherein a focus position of the side-viewing capturing optical system in the magnifying observation resides on an extension of the outer circumferential surface, the extension facing the cutaway portion in the side-viewing direction, and the extension of the outer circumferential surface resides within a depth of field of the side-viewing capturing optical system in the normal observation; and a switcher for passing light from one of the front-viewing capturing optical system and the side-viewing capturing optical system and blocking light from the other of the front-viewing capturing optical system and the side-viewing capturing optical system.