SIGMA 10-20MM F3.5 EX DC HSM

An upgrade over the original Sigma 10-20mm zoom, this edition gains a constant-aperture design

Like the original Tokina 11-16mm lens, the first edition of Sigma’s 10-20mm dates back to the early days of DSLR photography, and was actually launched in 2005. This newer edition is still ten years old and predates Sigma’s ‘Global Vision’ line-up of Art, Contemporary and Sport lenses.

This lens is nevertheless a significant upgrade and swaps from a variable to a constant-aperture rating, with f3.5 being available throughout the zoom range. As such, it’s two-thirds of a stop slower than the constant-aperture Tokina lens on test.

The optical design omits any top-drawer FLD elements, as featured in the Sigma 8-16mm lens, but up-market glass includes two ELD (Extraordinary Low Dispersion) elements plus one SLD (Special Low Dispersion) element. The build quality feels similarly up-market as in the 8-16mm lens, although also lacks any weather seals.

A bonus for landscape photographers is that, unlike the 8-16mm lens, this Sigma has a conventional bayonet-fit hood and filter thread, enabling the fitment of screw-in filters or a filter holder for square/rectangular filters. Even so, the thread is quite large at 82mm, matching that of the Tokina f2.8 lens.

As with the wider Sigma 8-16mm lens, this one features a ring-type ultrasonic autofocus system with the same advantages of speed, quietness and consistent accuracy. For image quality, centre sharpness is impressive at all focal lengths, but corner sharpness isn’t quite as good as from the competing Sigma and Tamron lenses. On the plus side, barrel distortion at or near the 10mm mark as well as colour fringing throughout the zoom range are particularly well controlled.