Sigma Lens Problem?

I recently purchased a Sigma 17-70mm zoom lens for my XTi. I had read a lot about and had noticed that some people had to exchange theirs for a "good copy."

I did a quick focus test when I got it to make sure it didn't have a severe front or back focus issue and it looked okay, except the right side seemed sharper than the left. I just assumed I hadn't lined up the camera accurately.

I then started using the lens. I took some family shots over Thanksgiving and noticed that the left side was consistently softer than the right so I decided to some more testing.

Well, it appears that the lens is out of alignment. The right side is consistently sharper than the center and the left side is pretty soft, in comparison.

I've talked to B&H Photo and they're sending me the return shipping info but I just am wondering if I'm making too big a deal of this. Here is a sample comparing the left side, center and right side. It's taken on a tripod at f/8.0 in Raw. The only PP I did was to adjust the levels and white balance. These are sections at full size (36" x 54" at 72 dpi.)

http://xs410.xs.to/xs4​10/06485/SigmaTest.jpg

Byte size: ZERO | Content warning: NOT AN IMAGE

how far away where u from the paper.
also how does it do when taking real pics not pics of trying to see if its messed up

What AF point are you using? I would also like to see some real world pictures.

It's a great lens but yours doesn't look so good. I would accept the replacement and try your luck. That does look out of alignment. I assume it was square on a tripod. If not the results can't be trusted. Seems like in real world shooting you had similar issues, in which case send it back.

what! i just order this lens yesteday i hope mine doesnt come like that ..

If that paper is for certain square to the lens then I'd swap it out or send it in.

nismosr I'm sure yours will be fine. It's one post.

I think this is the first I ever heard of the 17-70 not being up to par....I am sure this is only a rare case...

This isnt only limited to Sigma, ANY make of lens has duds knocking around, you can be unlucky with anything, if your even the slightest bit unsure you should send it back for an exchange.

The 17-70 is sharp edge to edge & definately should NOT be worse on one side, I make my 17-70 do everything, landscapes, the odd portrait, family photos, macro etc..

This is a recent shot I took using my 17-70, you should be getting very sharp results, if not then return it straight away, you dont want to be left with a lemon!

Byte size: ZERO | Content warning: NOT AN IMAGE

Definately get a replacement or get it serviced by Sigma. The 17-70mm produces sharp pictures all around, so why settle for a below par copy?

Great pic Nick_C. only resized or cropped too? I'm assuming PP, otherwise that's a brilliant copy!

Thanks egghead, that was uncropped, all I did was resized for the web with a little sharpening which is usually needed on DSLR images anyway.

It is a great lens, works very nicely on macro shots too.

Nick

Its a shame you got a bad copy, I can't believe how well liked it is around here, just shows how good it can be.
But, the more the sell, the more bad ones get through.

Hope sending it back is relatively painless, and the new one comes from the other end of the quality curve
At F8 it should be an awful lot sharper than that!
I know mine certainly is.