fatboybrando skrev:

Well, we call it a monday-issue. It is supposed to be more frequent from
Sigma than from Canon, Nikon etc., but as I see it from tons of
messages, all manufactors have that kind of problems.

Crappy images are often produced by Sigma products.

Give the old brick wall and/or newspaper test. If that shows a clear
problem, demand a replacement with that evidence.

Sigma's quality control is iffy at best. It took 3 trys to get a good
one the last Sigma I bought (4 years ago, was stolen) and that was
their 28-70 f 2.8 supposedly one of the best. BTW the third lens was
very good. As another person said shoot a brick wall, if one side is
sharper than the other take it back. Why not spend the $150 more and
get the Canon, folks who have used it say it is not a perfect lens, but
still very good.

Tom

Does it show up with any other lenses you have?  Sounds like
some kind of lens or sensor misalignment.
-Rich

Hi
I just bought the same lens 2 weeks ago for my Nikon D70.

The first photo's I took were on a bright sunny day the aperture was f16 and
no problems in fact sharper than I expected. But when I took some hand held
shots  on a cloudy day on much wider aperture I noticed the edges showed
some blurring. So I now know to use around f11 +. Not ideal but I reckon as
I can't afford the Nikon lens and most of my shots are landscapes using a
solid tripod it's acceptable.

Bruce

I've got one that produces extremely sharp images corner to
corner--surprisingly good. I've had and tried a number of Sigma lenses over
the years and this is by far the best. I read a review of this lens in which
the reviewer tried two examples, of which one was noticeably better than
another, so perhaps you should return it, or go to where you bought it and
at least ask them to let you try another to see if the problem is the same.

Toby