An optical device designed to provide the illumination and image transmission capabilities of a rigid endoscope. It typically includes a set of lenses (e.g., thin and rod-shaped lenses) and/or a fibreoptic bunch, and is introduced though the sheath of the endoscope (e.g., a rigid cystoscope or resectoscope). The endoscopic telescope is connected proximally to a light source, and the returning image is directly observed or scanned with a video camera. Dedicated types are available for direct, lateral, and oblique views. It is used for examination of body cavities following natural tracts (e.g., urinary, gastrointestinal) or surgical cavities (e.g., laparoscopic). This is a reusable device.