Sigma 18-35mm F1.8 DC HSM Art
The Sigma 18-35mm F1.8 DC HSM is an extraordinary lens, offering prime-level image quality in the fastest zoom ever made for SLRs. Its 28-50mm equivalent range is a little limiting though, and inconsistent autofocus means that it can be difficult to make the most of the excellent optics when shooting at large apertures.
Enthusiast APS-C users looking for the very best image quality available from a normal zoom, and willing to spend a bit of time setting up autofocus micro-adjustments or using live view focusing for the sharpest results.
Photographers who like to travel light, or need a wide-ranging zoom.