privatebydesign said:
It is true, the 16-35 f4 IS is a considerable image improvement over the 17-40 f4, and you get IS. Having got the 16-35 f4IS I wouldn't hesitate to recommend it to pretty much anybody.
I agree.
The 16-35/4L IS is a very big improvement over both the EF 16-35/2,8L II and EF 17-40/4L. I have over the last 10 years owned many copies of both lenses, got frustrated with the IQ, sold them and after a while bought them back because Canon had no alternatives. In the end I switched to Nikon and the AF-S 14-24/2,8 which I had for three years. The IQ was very good, but it isn't possible to use filters on the Nikon, which is very important for me, and it is very large and heavy. It was therefore a great satisfaction for me to try the new 16-35/4L IS which is very sharp, actually in the same class as Nikons 14-24mm.
16-35mm is the ideal zoom range in the wideangle area. 14mm is in my opinion too wide. Then it is better to use a 8-15mm Fisheye which I also own. If you know what you are doing, a Fisheye gives in many situations more natural pictures than a 14mm wideangle. Also with people in the frame.
Which lens I would choose? Not the Canon 11-24/2,8 or Nikon 14-24/2,8. You can't use filter on either of them. And both of them stop on 24mm. I then had to buy also a 24-70mm zoom because I need the 18-28mm area. Silly to switch between two lenses (Which I did for many years with the Nikon) when a single 16-35mm can do it all.
The winner? None of them! The EF 16-35/4L IS is the best. It is cheaper, lighter, more compact and it takes 77mm filters. Of course it lack f2,8 but instead it has IS which is more important! Especially with the new 5Ds 50Mpix camera. Nobody really needs f2,8 for landscapes or street photos/architecture. The DOF is then too narrow. F2,8 is of course great for photographing the Northern light, but then you can buy the 14/2,8L II instead?