Optische Vorrichtung

Apparatus (1) for use as an endoscope or borescope comprising an outer tube (2) having a distal end (3) which is insertable into an inaccessible location to be inspected and a proximal end (4) which is accessible to the user. A zoom lens is provided within the outer tube adjacent the distal end and is operable to focus an image with variable magnification at a focal plane within the outer tube. The zoom lens comprises an objective lens (7) which is fixed relative to the outer tube and two independently movable lenses (8,13). An elongate viewing means (43) is provided for viewing the image and extends through the outer tube from a location at the focal plane to a location proximal of the proximal end. A cam operated actuating means (29,21) is operable to move the movable lenses to change magnification and to synchronously move the viewing means relative to the objective lens to compensate for movement of the focal plane. Refocussing of the apparatus following adjustment of magnification is thereby carried out automatically.