This is a case of perspective distorsion. It'smore visiblewithwide angle lenses. My 17-40 L does the same.


It can be corrected by holding your camera level, you may have to elevate the camera to achieve a similar crop. Another way of correcting it would be a tilt and shift lens. You can also take care of it in post.


Perspective distorsions are very cool when used creatively.