Abstract: The main body of the operation section comprises a holding portion which can be gripped by a single hand, and a mounting surface to which are mounted operating buttons depressed in the direction of the axes thereof. The operating buttons are aligned in the direction of the axis of the holding portion. The axis of each of the operating buttons makes an angle of more than 90.degree. to 150.degree. with the axis of the holding portion as viewed from the holding portion. Also, the axes of the operating buttons get nearer toward the axis of the holding portion and make an acute angle.

Abstract: An endoscope system comprises an endoscope, a light source unit, and an auxiliary apparatus such as a camera unit or a dual viewing optical unit. The light source unit includes a discriminating circuit which discriminates the kind of the auxiliary apparatus when the auxiliary apparatus is attached to a viewing section of the endoscope. The discriminating circuit causes a solenoid energizing circuit to drive a solenoid in accordance with the kind of the auxiliary apparatus, thereby moving a stop to a predetermined position. In consequence, illumination light of a given intensity corresponding to the kind of attached auxiliary apparatus is led from a light source into a light guide of the endoscope. Thus, an image can always be observed with suitable brightness through the auxiliary apparatus or the viewing section of the endoscope without regard to the attachment of the auxiliary apparatus, as well as to the kind thereof.

Abstract: An endoscope connector comprises a cylindrical body detachably connected to a light source console and provided with an illumination optical fiber bundle and a fluid passage, an annular grooved communication chamber formed in the outer peripheral wall of the connector body to communicate with the fluid passage, a ring member rotatably surrounding the communication chamber in a fluid tightness, and a fluid-guiding fitting mounted on the ring member. Application of the ring member in combination with the annular grooved communication chamber reduces a length of time required to free a protective tube for coupling the connector to the endoscope from twistings which probably arise from the unavoidable rotation of the endoscope during insertion into a coeliac cavity, thereby decreasing the operation time of the endoscope.