josuke,


I have a 50D too, along with both the 17-40L and the 70-200 f4L (non-IS version). I can attest that they are both fabulous lenses that are pretty darn good value considering their price tag. I think you may find that the 17-40 is NOT as wide as you want it to be if you are truly going for wide angle and it might not get used as much as you want it to since a considerable amount of its range is overshadowed by your 24-105, which has IS, and that is soooo nice. I love image stabilization.


Personally, I have never used the Canon 10-22, but there has been enough praise sung about it that you really couldn't go wrong with it. I have the Tokina 12-24 f4 and it is in somewhat of a different class from the Canon 10-22, but it still takes quality images (I would feel comfortable blowing up to 24x36) and is considerably cheaper than the Canon 10-22. In all fairness, I have to say that if my budget permitted, I would have purchased the 10-22 [U]. As it is though I would rather have a Tokina 12-24 AND a Canon 85 1.8 than just a 10-22, so thats the way I went. [H]


Good luck on your decision. If you have more questions, holler!


Cheers,


Dave.