A rigid endoscope including: a fiber tube a window disposed at a the distal end of the fiber tube an objective lens arranged in the fiber tube a spacer tube to maintain the objective lens at a predetermined-distance from the window and an objective lens tube for holding the objective lens, the objective lens tube being disposed in the fiber tube between the window and at least a portion of the spacer tube wherein the spacer tube is supported on a distal end against the window and on a proximal end against the objective lens.