200mm f2.8 IF                                                         100mm f2 + 2X-B                                    100mm f2 + 2X-A

200mm f2.8 IF                                                                100mm f2 + 2X-B                                        100mm f2 + 2X-A

200mm f2.8 seems a little softer but just as sharp as the 100mm f2 + 2X-B combo. Surprisingly the 2X-B gave very nice contrast.Using a 2X-A on lenses below 300mm does deteriorate the image.

                                                                                        100mm f2 +                                     300mm f4 L

                                                                                        Auto Teleplus

                                                                                        3X Converter

This is what happens when you add a generic 3X multiplier to a good lens. That's probably why Canon never made a 3X !!!