There’s not much to choose between the two Sigma lenses in terms of performance. Levels of distortion and colour fringing are controlled fairly well in both cases. The 18-250mm is slightly sharper in the 18-200mm segment of its zoom range, but drops off noticeably at its longest telephoto setting. Before the advent of the Nikon 18-300mm VR, this lens boasted the biggest zoom range of any superzoom on the market. It still looks an attractive proposition, with an ‘effective’ range of 27-405mm and the inclusion of Tamron’s VC (Vibration Compensation) stabilisation system, which is typically effective. Moreover, it’s a redesigned and more compact VC component than in the original Tamron 18-270mm, which contributes to a smaller, more lightweight build.
Another upgrade in this edition of the lens is the inclusion of a PZD (Piezo Drive) autofocus system. It works in essentially the same way as the