It took me a while to get to the 16-35 2.8L (scared off by the price). For more than a couple of years I was shooting with a Sigma 15-30 and I was actually quite happy with this lens.

When I needed a second wide zoom I jumped for a used 17-40 4L, which I was quite happy with except for a couple of issues. I think the main one was focusing. On the 20D the 16-35 2.8L just seems to get it right more often than the 17-40L. I guess this may have something to do with the cross sensor focusing kicking in with lenses f/2.8 and faster on the 20D. The other obvious advantage is the extra 1mm, which makes a huge difference on 1.6x crop camera.

I love the fact that the 16-35 2.8L is sharp wide open and enjoy the colour and contrast it produces. I find it worth the step up..