The invention relates to an image transmission system for rigid endoscopes, having a central rod lens and two outer rod lenses, which are symmetrical in respect to one another in relation to a vertical central plane of the image transmission system relative to the optical axis, wherein all lens elements consist of optically homogenous material, all optically active surface are spherical and two lens elements are stuck to on another facing each other or facing away from one another on the opposite sided of the central and outer lenses in the main lens elements of the rod lenses so that the resulting composite lens is biconvex. According to the invention, the rod lenses are arranged apex to apex next to one another and the central rod lens is substantially as long as or longer than the outer rod lenses. The solution according to the invention provides an image that is as light as possible at a given transmission length, wherein the structure of the rod lens system is simple and imaging errors can be corrected as in prior art. The number of components and production complexity are low.