Hi guys. I just got some pictures developed, and there appears to be some vignetting in the upper-left hand corner, and no other corners. I was under the impression that if you get vignetting, it'd be in all corners of the picture, is this not the case? It was taken with my Canon 24-85mm lens (with a lens hood on), at the 24mm angle. I've got some other shots taken at 24mm and none of them have any vignetting in them. The only thing I can think of that was different in this one picture was that I was aiming the camera up a bit (to capture the sky). Is this likely just a weird, isolated incident or something I should expect to happen more often?