Rod lens systems use special glass rods with optically finished ends, providing images with higher brightness, contrast and colour reproduction than conventional lenses.
Commonly, rigid endoscopes have a series of high-resolution optical glass rod lenses. The endoscopes can be forward viewing (0 degrees) or angled (10–120 degrees) to allow visualization out of the axis of the telescope and increase the FOV by rotating the instrument. The optical quality of lens-generated images of rigid endoscopes still surpasses that of the fiber-optic or digital images produced by flexible scopes.