All four varieties of the Canon 70-200mm "L" zoom are renowned for being ultra-sharp. This is the Rolls Royce of the range, the f/2.8 IS version. It's the longest of the four, and the widest, and the heaviest and by far the most expensive. It's also the most flexible - if you're prepared for the weight and the expense, you don't need to choose between the constant f/2.8 or the IS - you can have both. If you're shooting moving subjects though, then IS isn't much of a help, and you might find the f/2.8 non-IS version a better choice.

This lens can be used very well with a Canon Extender (teleconverter). The 1.4x Extender makes it a 100-280mm f/4 zoom, and the 2x Extender makes it a 140-400mm f/5.6 zoom. With either Extender, the lens will still autofocus on all EOS cameras.