I bought the Sigma 70-200 2.8 and had problems with motion blur I prefer to shot at 100 iso and hand held. I sold that lens and got the 100-400 Canon IS and have been very happy with it's performance. I still have to use a monopod in low light, I like the mobility of the monopod because I walk allot while looking for shots. I also had the 100-300 Canon IS and it was a nice clean lens for hand held shots. I used it to cover a couple of races it's a great lens if you can get the 100-400 IS right now. I can direct you to a photo gallery of the races I used that lens on if you would like. Randys