2 weeks ago, I got a Tamron 28-75 from BIC camera in Japan. When I came home, I made a simple newspaper test realized that the corners were incredibly soft. Next day, I took it to the shop and asked for a replacement. They took some test shots by themselves and accepted to replace it. Before accepting the new one, I wanted to test it in the store. Unfortunately, it was worse than the first one and they did not have another sample. So, they refunded my money.
On my Trip to Tokyo 2 days ago, I purchased this lens again with the hope that the 3rd copy will not have this issue. I did not have time and I made a very quick test in the shop and it seemed fine. But when I came home, I realized that I was wrong. Now, I have a FF problem together with very obvious left bottom corner softness (centering problem I guess).
Now, the problem is, I do not live in Tokyo and I cannot take the lens to the camera shop for a refund or replacement. I really want this lens and I think the fourth copy will have a similar issue anyways. What I am willing to do is to send this lens to Tamron Japan and ask for a calibration. Is this possible? Do you know the contact adress of Tamron Japan? In their English section of their web site I could not find any contact information.
PS: I have a K10D which focusses perfectly with FA35 and DA70. I am sure that my K10D does not have a FF/BF problem.
AF corner %100 crop, 75mm/f2.8:
Another photo at 75mm/f2.8: (Does not allow me to upload the original file but even from this photo the problem is evident.)