Techniques for replacing and eliminating paths causing channel leakage current. Furthermore, the fire-control riser system comprises an enclosure that provides for easier installation, pre-assembled components and protects such riser systems from damage during the construction process. The camera lens system satisfies the conditions in which a focal length f1 of the first group lens is within a range of 4. A unifying unit makes a construction of the unit while, on the other hand, a navigation data producing unit depicts navigation data at a foremost position of the unit.