Hello,

I am thinking about getting a 5D III and also the 2.8/24-70L II.
This will be in addition to my 7D which will be used mostly for shy animals when I have the 5D III. Now I use the EF-S 10-22 but with a FF body I can sell this lens and will have one lens less to carry - great in the mountains when carrying all the stuff. Other reasons for 5D III are even better AF and better IQ.

I love my 4/17-40L on the 7D (or my old 40D, 10D) but saw some shots on the web with terrible lack of sharpness in the corners. Got better when stopped down to f8 or f11 but still not very good. Results
are different on different reviews on the web, though.
I can live with the corners being a little worse than the center and don't expect the 4/17-40L to be as good as Nikon's 2.8/14-24 but I want to make rather large prints of some landscape shots (the IQ of the 5D III should be amazing for this) with 60x90cm or even 80x120cm. Of course this is a lot and I don't expect miracles but it would be interesting to see how the 4/17-40L works on the 5D III for landscape shots, particularly from 17-24mm as I will probably use the 24-70L II for anything with 24mm or more as this should be an awesome lens once available.

If you have any sample shots with the 5D III and the 4/17-40L can you please post some 100% crops of parts of the image, maybe center and corner? This would be very interesting.

Thanks,

Markus

Markus,
This is the direction I went (Tokina 16-28). I hope to get some tripod pictures in the morning. I have only used it hand held from a kayak and on a horse ride so far but I have no complaints from what I have seen. Corners are soft wide open. It is the first time I have purchased a lens that was not a Canon lens and I have to say I like it. I have also found the 5DIII to be a great all around camrea in the back country.
http://www.photozone.de/canon_eos_ff/595-tokina162828eosff

I use the 17-40mm in my new 5D-III but not tried still in depht. My 17-40 seems to work well with that camera in centre and right corners if closed to f:8-11, but not so good in the left corner. At f:4 really not good in the corners. But it was not good already in my cropped 1D-IV sensor.

But the corner quality improves A LOT with the new Canon DPP software Digital Lens Optimizer.

Thanks for the comments. Very helpful. On my 7D it is very sharp in the center, particularly with f8 or f11. Maybe it will work in the corners so IQ will be sufficient. I will also try the new Cano DPP but hope that Lightroom 4 can also do the fixes.
The Tokina also looks interesting.

Markus

On the 5DII the 17-40 is sharp in the centre but loses it towards the corners. I kind of like the effect though. It will not be better on the mkIII, the only choice then is the large and bulky 16-35...not to mention pricey

Tokina looks interesting though.

Have a look on the digital picture.com. They have test chart crop images of most of the contenders.

Compare the images to the zeiss 21 mm which is about as good as it gets.

Not neccesarily suggesting the zeiss just that it gives you an idea of what you are giving up in corner quality.

Ther lenses mostly tested on a 1DsMkiii so are pretty close to what you expect out of a 5Diii .