Many reflecting and refracting elements are required in the construction of a conventional optical system with a low f/number. Such a system poses problems in alignment and mechanical stabilty when operating in severe environments over a wide temerature range. A fiber bundle designed in the form of a cone with larger entrance diameter than the exit diameter transmits and reduces the uimage size. A simple lens of longer focal length and larger effective aperture can be used to produce an imageat the entrance of the cone. Since there is a gain in flux per unit area, this system intesifies as well as trasmits an image. It also enables the use of a detector of smaller size to achieve a higher signal-to-noise ratio. An effective optical systen for doing this is described and demonstrated.