Sigma 17-50mm f/2.8 EX DC OS HSM FLD Large Aperture Standard Zoom Lens for Canon Digital DSLR Camera - International Version (No Warranty) For Canon DSLRs with APS-C Size Sensors 4 Stops of Anti-Shake (OS) Compensation Aperture of f/2.8 throughout Zoom Range Accepts 77mm Filters Ultra Compact (Only 3.6", 91.8mm Long) Multi-Layered Lens Coating Excellent Correction for Aberrations Hyper-Sonic Motor for Quiet/Fast AF Close Focusing Distance of 11" (28cm) Weighs Only 19.9 oz (565 g)