Canon 17-55mm f/2.8 – tilted lens element?

Last month, after much agonising, I purchased a Canon 17-55mm f/2.8 IS USM lens, which I couldn't be more pleased with. I can scarcely believe the difference from my previous 18-55mm IS II.

Over the weekend, though, I noticed something odd at 17mm – the lower right corner seemed quite smeared on one particular test shot (I won't post the full image as it has no redeeming features whatsoever...). I tried turning the camera upside down and taking the shot again (the image on the right) and the softness in that shot roughly matches that in the other non-affected corners.

I tried the same shot twice more and each time had the same result. The strange thing is, it hasn't been as noticeable on any other picture I've taken. The 'tilted' image on the left is actually slightly sharper in the centre than the one on the right (the shutter speed was 1/640). As far as I can tell, the rest of the zoom range has no problems.

Here's the opposite corner that the softness should have switched to (on the right) when I turned the camera upside down. To my (distinctly untrained) eye, they both look fairly close – but perhaps the upper left was slightly smeared in the first one, too?

Is there anything else that could be causing the blurring in the first image or could it only be caused by a tilted lens element? Unfortunately, the 30-day returns period for the lens runs out tomorrow, so I'd have a difficult decision to make if it does turn out to be faulty; the lens in incredibly sharp at f/2.8 and I'm unsure how much sample variation there is between 17-55s.

Thanks for any help.

I had two copies like this a few years ago i and gave up. I got another last month and that had similar issues, so gave up.

Its a shame as i had one for about 5 years when they first came out and out was perfect.

Sorry, i don't have much to add, other than is it a big deal if not pixel peeping? I understand where you are coming from but maybe its just something you will learn to live with (I couldn't though).

I think you made the right decision. It's not a major issue most of the time but like me, knowing good its there will bug the hell out of you and you become obsessed.

I too only noticed it on distance shots, and mostly with a lot of detail at the edges. Indoors for room size shots it was never an issue. Even stopped down i could never cure it.

Back when i had my first one i had it on a 30D, then a 40D and finally a 60D. No issues with any of those. I did sell it to get the 15-85, and had no issue with that either. It was a few years later i tried to get another 17-55 and both copies had a soft lef hand side. This more or less pushed me in to getting a 5Dmkiii. Four years later and I got my 80D and again, tried to get another 17-55. This time it wasnt too bad, but i felt it was still not good enough. Considering all my cheaper EF-S lenses had no issues i again gave up on this lens.

Good luck with the replacment.