Mid-hui, edges Pooh!

I had before actually, my standard zoom Nikkor AF-S DX exchange 18-70 f / 3.5-4.5 ED against a light stronger lens. This objective should be according to various test reports (photozone.de, dx0mark.com etc.), as far as the point of focus, very well, even better than the successor model with Image Stabilizer (VC).
Such tests are in favor of a first clue good but ultimately recognize the weaknesses only when it committed itself in practice. And there was very quickly in direct comparison that although there are very well reflects in the image center, but sometimes visible but strongly decreases the edge sharpness, not to say clearly soft. That's too bad, because that it is absolutely unsuitable for photographs of starry sky at the short end at open aperture, which I would have also liked to use. In addition, my right half seems to be sharper than the left, indicating a slight decentering. Perhaps it could be the fix by adjusting the Tamron Service, but I have to be honest to become the second copy no desire to play the final quality of the work in China. And it is certainly not on the camera housing, as with other lenses shows this weakness is not in the left half.
All in all I'm very disappointed, but before I give away my Nikkor, has to find a lens that is actually better for now.
Below are a few comparison shots. Who would like to see more comparative pictures, DSLR-Forum takes the theme "Comparative AF-S DX Nikkor 18-70 f / 3.5-4.5 with Tamron 17-50 f / 2.8 (VC)" a link.