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Verdict: This lens is one of the more affordable wide-angle lenses and with a constant aperture of f/3.5 it creates a pleasing background. It’s not as sharp as other lenses we’ve reviewed but has many good qualities.
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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.
Image quality
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.
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Spec
Mounts: Canon, Nikon, Pentax, Sigma and Sony
Min aperture: f/22 Elements: 13/10
Filter size: 82mm
DxL: 87x88mm
Weight: 520g
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Kirk Schwarz is a tech-addicted photographer with over a decade's experience; Kirk’s used to putting new gear through extreme field testing. He's previously written for Practical Photography.