Tamron SP AF 17-50mm f/2.8 XR Di II VC LD £380/$650
THIS OLD-SCHOOL ZOOM STILL HAS SOMETHING TO OFFER
Now eight years old, this Tamron lens combines a fast, constant f/2.8 aperture with VC (Vibration Compensation) stabilization.
It competes directly with the Sigma 17-50mm for zoom range, aperture rating and stabilization, and is almost exactly the same size and weight. Unlike the Sigma, however, the Tamron has a smaller filter thread of 72mm instead of 77mm; doesn’t come with a soft case; and has a more basic electric autofocus motor. The optical path includes an XR (eXtra Refractive Index) element, two LD (Low Dispersion) elements and BBAR (Broad-Band Anti-Reflection) anti-reflective coatings.
Autofocus speed is a little quicker than in the DX-format Sigma lenses, but the motor is comparatively noisy. Again, the focus ring rotates during autofocus and there’s no fulltime manual override. Centresharpness is excellent at short to mid zoom settings but cornersharpness is relatively poor at both ends of the zoom range.