best lens in this range

This lens is large, heavy and fairly expensive (aprox. $1600), but if you take pictures at action events, or candid shots of wildlife, you will find nothing else that will give you the range and quality of pictures that this lens will.
You can buy a lot of cheaper lenses(at least in the 70-300mm range)but you get what you pay for. This lens has great sharpness,great clarity, no distortion, a range of 100-400mm, whisper quiet focusing motors, very fast auto-focusing, and IS (this stabilization can be a great help when your hand holding your camera in less than perfect lighting situations).
My wife and I like to do candid nature photography. We try to capture, in pictures, the flora and fauna around us. My wife is especially fond of photographing birds. She had been using a Nikon 6006 with an inexpensive 70-300mm lens (aprox $300). The results were often disappointing. The sharpness and clarity were never there. Plus, since many of the shots were in low light conditions, blurring caused by not being able to hold the camera steady was always a problem. The lens and camera were also so noisy that often just the sound of the lens trying to auto-focus scared the subjects away.
My wife than decided she had had enough of ruined opportunities, and decided to invest in a Canon Elan 7E and the EF 100-400mm lens. We have been very happy with the results. The picture quality is so much greater its hard to believe. The better optical quality of the lens, super quiet
quick auto-focus, and the IS feature, have made the difference. It may not be small, light, or cheap, but we would not want to be without it.