Tamron SP 15-30mm f/2.8 DI VC USD lens gets 31 points DxOMark lens score and a peak sharpness of 24P-Mpix, it is an exceptional performer. And the Tamron SP 15-30mm f/2.8 has very high center sharpness at all focal lengths, even wide-open at f/2.8.
From DxOMark conclusion:
All lenses are a compromise, but the Tamron has a good balance, with high central sharpness wide-open and sharpness improving across the frame on stopping down, and with generally good control of chromatic aberration. On the downside, it has some slight field curvature at 30mm and it has quite high levels of both barrel and pincushion distortion that are more noticeable than the Nikkor equivalents.
However, at least the Tamron doesn’t exhibit complex distortion, so it should be relatively easy to correct with software. In physical terms, the lens is large and heavy and doesn’t cover the popular 35mm focal length, but as a 24-47mm equivalent on an APS-C-format DSLR, it remains a versatile offering. Combined with its good performance and the lure of built-in stabilization, at around $1,200 it looks very tempting.
Tamron SP 15-30mm f2.8 Di VC USD (A012) vs Tokina AT-X 16-28 F2.8 PR FX: Good central sharpness
Tamron SP 15-30mm F/2.8 Di VC USD (A012) vs Nikon AF-S Nikkor 16-35mm f/4G ED VR vs Nikon AF-S Nikkor 14-24mm f/2.8G: Competitive optical performance
Against the one-stop slower yet stabilized Nikkor 16-35mm f/4, the Tamron is the slightly better performer. It has higher sharpness at f/4 than the Nikkor over the wider focal lengths, while more or less matching it at its longest, and of course the Tamron isn’t bad at f/2.8, either.