Canon 100-400mm f/4.5-5.6L IS USM

Stupidly sharp lens - forget the Bigma, or even Canon's own 100-400L, if you are a wildlife photographer, this ticks every box. Not the fastest lens, but so what, you still get an excellent hit ratio with something which is so incredibly powerful. Its not just the sharpness either, its the light and colour quality this lens delivers.

Sports photographers will be frustrated by lack of zoom and needing to be a decent distance from the subject, but as I say - wildlife and esp. bird photographers - this is the one.

As a wildlife photographer without the means to purchase lenses costing more than $2000, I use the Canon 100-400mm f/4.5-5.6L IS USM lens more than any other and have been extremely happy with the results. The image stabilization makes it possible to hand hold it in many situations that usually require a tripod and still get sharp pictures. The zoom range offers real flexibility - a plus if you hate to change lenses or don't have the time even to switch cameras.