The Sigma 10-20mm f/3.5 EX DC HSM is an ultra-wide-angle zoom lens built for Canon APS-C DSLR cameras, delivering impressive creative versatility for landscape, architectural, and interior photography. This secondhand lens features a constant f/3.5 maximum aperture throughout the entire focal length, a rare specification in this focal range that ensures predictable exposure and enables shooting in challenging low-light conditions without compromising shutter speed. The optical design incorporates premium low-dispersion glass elements and four aspherical elements to minimise chromatic and spherical aberrations, whilst a super multi-layer coating suppresses flare and ghosting for enhanced contrast and colour rendition. The Hyper Sonic Motor (HSM) delivers fast and quiet autofocus with full-time manual focus override, making this a practical tool for both studio and field work. At 24cm minimum focus distance throughout the zoom range, the lens accommodates close-range work and delivers excellent optical performance across its entire focal length spectrum.