EFS 17-55 USM corner blurriness: experts' opinion needed !

I think that everyone at the school where my favorite brick wall resides think I'm positively crackers. I stand there for 20 minutes, half an hour or more with my camera on a tripod pointing at a wall. Meticulously taking shots and changing lenses - they must wonder what sort of pictures I wind up with.

Regardless, I take shots with every lens I get. Normally it's just going through the motions as I've never yet suspected one of my lenses of having decentering issues. If I did, I'd go back and rotate the camera as MAC mentions.

And, a hedge works well too. The brick wall can help show you the distortion, and unevenness of distortion for example, as well as giving you a grid to guide where softness starts. The brick wall also is most useful if the decentering is subtle - I don't think we're talking subtle here.A hedge is also good at showing detail, color, light and shadow and how a lens handles it. As you can see below - I use one in my backyard frequently. I'm about to go out there and try out my new Tamron 150-600 against my 70-300.

Honestly, I don't have any lenses with soft corners - or at least one corner that's noticeably softer than the others. Usually a quick set of snaps on the brick wall confirm there's no problem, and I've not gone out to it suspecting (knock on wood).

The 17-55 is an excellent lens for a reason - but Roger Cicila claims that it's also quite fragile. When it comes to lenses and lens issues - I'll call him an expert.

http://www.lensrentals.com/blog/2009/05/lens-repair-data-3-0

Anyway, I'd return it and hope for a good copy. It can happen.

I had 4 bad copies of the Tamron 70-300 VC. From non-operational, VC problems to front focus problems. I waited a year and a half, and then got a good copy my first try. When I got my 6D with 24-105 kit, I got an incredibly soft 24-105. But it wasn't so soft that I thought anything was out of the ordinary - especially when most people here said to MFA the thing, or that the Sigma I was using to compare (my only other FF lens I could use at the time) was a lot sharper. I finally figured, if it stank on my 60D, I couldn't MFA that, so it went back. The new one was so much better it wasn't even funny. With MFA it went from good to borderline excellent.

So don't feel bad at returning it again - especially based on your example. It happens, and it's your money.

24-105

24-70

16-35/4

17-40