I used canon 400D w/ EF28-105 so it's noway to shot wide-angle landscape with this lens... but there is a way
This photo below used 8 pictures to make such a wide one photo.
and why do we need a wide-angle lens???
of course, the progress to combine 8 pictures into one big photos isn't a clever way to make a wide-angle photo...
I used photoshop to make and in this part... it took me almost 2 hr.to be done.
so... yes, go buy a wide-angle lens!!!!