The 17-40 is not much wider than the 18-55 kit lens, which you likely came with your camera. If you are simply looking for a better lens in that range for a APS-C camera, you would be much better off with the 17-55 f2.8.


If, however, you want a wide angle, you want something on the wide end at 12mm or less. The only Canon-branded option is the 10-22. There are, also a number of third-party ultra-wide lenses which you might want to consider as well.


I have the 10-22 and love it. Since I do a lot of hiking and like to get wide panoramas it was the first lens I added to my kit.


-joe