I have the intermediate rings with a Canon EOS 50D and a Canon 100mm Macro lens, 1: 2.8 L IS USM connected. One can thus not automatic extension rings "3-piece 31mm, 21mm & 13mm" for macro photography to fit Canon EF / EF-S EOS 1000D, 300D, 350D, 400D, 450D, 500D, 550D, 40D, 50D, 60D, 7D, 5D Mark II, 1D Mark IV, 1Ds Mark III, 1D Mark III (metal bayonet) well set much closer to the approach motif and tiny details in the picture. From a normal lens like the 18-200mm can thus indeed make any Marco lens, but again, naturally reduces the distance to the subject greatly. Since there is little loss of light, one must remember to correct the exposure upwards. The intermediate rings serve their purpose fully, you do not need the 3 times as expensive original rings.
I would like to highlight the good service the company pulse photo !! The intermediate rings supplied are initially engaged not quite satisfied on the lens. A call was enough, in 3 days, the new rings were there, along with a return receipt, which allowed a free resending other rings. I call good service.
