The 135mm I believe to be the sharpest lens Canon makes, but in every test I read about, the 135mm with the 1.4 extender can't match the IQ of the 200mm 2.8 L. I have the 200mm. It is a GREAT lens and I use it for many things. For sports... hockey football, baseball, etc. Its also a great length for candids and nature, but it also makes a great lens for long portraits. The creamy bokeh and the compression make for a nice portrait combination. I think its a great focal length for a variety of uses. The 70-200mm zooms are great, but they're heavier and more expensive. The 200mm 2.8 is also sharper wide open, and its black which is better for candid photography.