Sigma's budget ultra-wide zoom for APS-C DSLRs, available across all major mounts.
The Sigma 10-20mm f/4-5.6 EX DC HSM was introduced in 2004 as one of the first dedicated APS-C ultra-wide zoom lenses from a third-party manufacturer, providing a 15-30mm full-frame equivalent range for Canon, Nikon, and other APS-C mount systems. The HSM (Hyper Sonic Motor) enables fast, near-silent autofocus compatible with Nikon bodies including D40/D40x that lack an internal AF drive. The EX designation marks it as Sigma's professional tier with higher-quality manufacturing standards. The DB entry covers the Canon EF-S mount version.
The optical design uses 14 elements in 10 groups, including aspherical and special low-dispersion elements for wide-angle aberration control. Six aperture blades produce out-of-focus rendering at wider apertures. The 77mm filter thread is notably large for an APS-C ultra-wide lens — appropriate for the scale required at 10mm — and matches the Canon L-series professional standard for potential filter carry-over. At 470g the lens is moderate in weight for its angle of coverage. Minimum focus distance of 0.24m enables close foreground-to-background ultra-wide compositions. Variable aperture runs from f/4 at 10mm to f/5.6 at 20mm. The HSM motor is fast and near-silent.
For APS-C landscape, architecture, and interior photography the 10-20mm provides ultra-wide coverage with a 15-30mm full-frame equivalent range. The 0.24m close focus enables foreground subjects in the lower frame while the background extends broadly — a technique characteristic of ultra-wide landscape composition. The HSM motor extends autofocus compatibility to Nikon D40/D40x and other bodies without screw-drive AF. Optical quality is good at mid-apertures in the centre; corner performance at 10mm wide open shows the expected characteristics of a wide-angle design at this price tier.
On the used market the Sigma 10-20mm f/4-5.6 EX DC HSM is affordable. The lens is available in multiple mounts — confirm the mount version matches the target body before purchasing. Condition checks: HSM motor response, front and rear elements for marks or haze, and zoom ring smoothness. The Sigma 10-20mm f/3.5 EX DC HSM provides a wider maximum aperture at a moderate premium. For Canon EF-S users, the Canon EF-S 10-22mm f/3.5-4.5 USM is a native alternative at a similar price point. Compatible with all Canon APS-C EF-S DSLR bodies and via EF-RF adapter on Canon RF APS-C bodies.