Sigma's ultra-wide for APS-C — the 10-20mm HSM covering dramatic wide angles.
Sigma produced two iterations of the 10-20mm wide-angle zoom for APS-C DSLRs: the 10-20mm f/4-5.6 EX DC HSM (2004) and the improved 10-20mm f/3.5 EX DC HSM (2008). Both deliver an extreme wide-angle view equivalent to approximately 15–30mm on full-frame across APS-C cameras, with HSM (Hyper Sonic Motor) silent autofocus. DC indicates APS-C image circle.
10–20mm zoom range, f/3.5 (newer) or f/4-5.6 (older variant) maximum aperture, DC APS-C formula, HSM silent AF motor, Nikon F mount.
The 10–20mm range gives an ultra-wide perspective well-suited to architecture, interiors, and landscape photography. At the extreme wide end barrel distortion is present but correctable in post. The f/3.5 constant-aperture variant is more consistent for video. Using this lens on a Nikon full-frame body will cause heavy vignetting — it is designed for APS-C only.
Verify which variant is present (f/3.5 or f/4-5.6) before purchase — the f/3.5 is newer and preferred. Inspect for fungus, haze, and coating condition. Test HSM AF motor. Confirm mount contacts are clean.