Kenko Close Up Filter turn a normal lens into a macro lens by reducing the lens' minimum focusing distance. The advantage of the close up filters over extension tubes is that there is almost no light loss. Kenko recommends placing the camera on a tripod when using these filters. The close up filters are available separately. They reduce the minimun focusing distance to the following: +2: f500mm +3: f330mm +4: f250mm f=infinity focus.