Photo answers review
Photo answers rating 
Features & handling This is a well-designed lens that feels really nice. The zoom ring is a good size and has a positive feel to it. The focusing ring is very loose in manual mode, which is a bit disappointing considering the rest of the build. Tamron has constructed the lens with 19 elements in 14 groups and there’s just the seven aperture blades – you may have expected more for the price.
Performance Considering this lens is an APS-C optic, focusing performance from centre to edge of frame is quite disappointing. At f/2.8 the lens struggles to provide pin-sharp focus in the middle, let alone the edge. At smaller apertures, performance does improve, and also at longer focal lengths it starts to get better too.
There are certainly signs of aberration on the edges of our test chart’s contrast disc, and this gets more obvious at shorter focal lengths and wider apertures. The level is not unacceptable though, and despite being visible it’s not distracting on your final images.
As this lens has a shorter focal length, it’s bound to show more distortion. Despite this, the performance can be compared to a 24mm on a full-frame sensor as the lens actually offers the 35mm equivalent of 25.5mm. The results therefore were not brilliant, as the lens produced quite excessive edge distortion in our tests.
Verdict Performance is rather disappointing for the £530 asking price, but the lens is very well made. The focus and zoom rings make handling easy and the image stabilisation (VR) works well.
The Tamron 17-50mm is surprisingly lacking in a number of areas. The sharpness is poor and images lack strong definition. You have a shorter focal length, but the downside is that this increases lens distortion too.
Specifications Filter diameter: 72mm
Weight: 570g
Dimensions (HxW): 94.5x79.6mm
Max. aperture: f/2.8
Min. aperture: f/32
Min. focus distance: 290mm
Lens hood: Yes
Image stabiliser: Yes
Format & fittings (FF=full-frame): APS-C; Canon, Nikon D