The Sigma 18-50mm f/2.8-4.5 DC OS HSM Zoom For Canon D-SLRs is a lens dedicated to digital SLR cameras with APS-C size image sensors offering a large apertureand Sigma's Optical Stabilization and provides a high level of optical performance. The large aperture of f/2.8 makes capturing exceptional photos in low light achievable, and the wide angle is well suited for indoor photography. It offers superior peripheral brightness as well as a compact and lightweight construction. Two SLD (Special Low Dispersion) glass elements and three Aspherical lenses provide excellent correction for all types of aberrations. The Super Multi-Layer Coating reduces flare and ghosting. Designed with inner focusing and inner zooming systems, high image quality is assured throughout the entire zoom range. This lens has a minimum focusing distance of 11.8 inches (30cm) throughout the entire zoom range and a maximum magnification ratio of 1:4.1.