The Sigma 10-20mm f/3.5 EX DC HSM is available for Canon, Nikon, Pentax, Sigma and Sony mounts...
Once the APS-C crop factor has been taken into consideration, the lens offers an effective focal range of 15-30mm.
The aperture can be set to a maximum of f/3.5 throughout the zoom range and creates a pleasing background blur. Sigma’s internal HSM (Hyper Sonic Motor) offers quick and quiet autofocus, while the focusing itself can be set as close as 0.24m with full-time manual focus override.
The lens houses 4 aspherical lens elements, 2 ELD (Extraordinary Low Dispersion) elements and an SLD (Special Low Dispersion) element to keep distortion and chromatic aberration to a minimum. The glass also features Super Multi-Layer coatings to keep ghosting and flare at bay. This 10-20mm lens boasts 13 elements arranged in 10 groups, and weighs 520g.
With the zoom set to its widest setting, the Sigma produces a slight amount of barrel distortion, but this is easy to fix when editing. At f/3.5 we found the corners of test images to be slightly soft, along with some subtle vignetting. At f/8 the image was sharp and bright across the frame, but instances of chromatic aberration appeared throughout testing. The performance was better at 20mm, with sharper results and less coloured fringing.
Most affordable wide-angle lens
Not as sharp as some others
Larger thread size makes filters more expensive
Mounts: Canon, Nikon, Pentax, Sigma and Sony
Min aperture: f/22 Elements: 13/10
Filter size: 82mm