Tamron 28-75mm f/2.8 SP AF XR Di LD - £355/$450
With a fairly conventional zoom range of 28-75mm, this Tamron lens lacks wide-angle coverage compared with Nikon and Sigma's 24-70mm lenses. On full-frame DSLRs such as the D700, it's noticeable how much less width there is in the maximum angle of view. On a DX body, any wide-angle potential is completely lost.
Build quality and handling are on a par with Tamron's slightly cheaper 17-50mm lens, being adequate but not impressive. The full-frame lens is much slimmer and has a fairly small 67mm filter thread, despite its large f/2.8 constant aperture.
However, unlike the Tamron 17-50mm VC, this lens lacks optical stabilisation. The basic electric motor that drives autofocus is slow and loud.
Mounting this lens on a DX body flatters its performance. Sharpness is quite good from corner to corner, and vignetting is also very low, even when you're shooting at 28mm at f/2.8. On a full-frame camera, though, edge sharpness is poorer. In both cases, contrast is a little on the low side, especially when light conditions are gloomy.
Sharpness test
On a full-frame body, sharpness around the borders is a little lacking, but it's not so noticeable on DX cameras.
Lab test at f/8
Sharpness at wide angle: 2262
Sharpness at mid range: 2287
Sharpness at telephoto: 2079
Fringing test
The worst lens in the group for fringing, most noticeably at the edges of the frame at wide-angle settings.
Lab test at f/8
Fringing at wide angle: 1.42
Fringing at mid range: 1.21
Fringing at telephoto: 0.32
Distortion test
Fairly little distortion at any zoom length. This is the most impressive facet of the Tamron's image quality.
Lab test at f/8
Distortion at wide angle: -1.48
Distortion at mid range: -0.48
Distortion at telephoto: 0.5
Image quality verdict
It's not a star performer on DX cameras, and no match for the Nikon and Sigma 24-70mm lenses on a full-frame body.
