The staple Sigma 50mm 1.4 DG HSM has been redesigned and reengineered to set a new standard for the Art line. With a large 1.4 aperture, the Sigma 50mm 1.4 prime lens is a pro level performer for shooting everything including portrait photography, landscape photography, studio photography and street photography. A Hyper Sonic Motor (HSM) ensures quiet, smooth and accurate autofocusing and paired with Special Low Dispersion (SLD) glass and Super Multi-Layer coating, the 50mm 1.4 is a high performance lens for the modern DSLR sensors. 13 elements in 8 groups allow for unsurpassed performance even at wide apertures and close-up photography is easily managed with a minimum focusing distance of 40cm. The Sigma 50mm 1.4 lens is the new exceptional standard, standard prime. SPECIFICATIONS Lens Construction 13 elements in 8 groups Angle of View (35mm) 46.8? Number of Diaphragm Blades 9 (Rounded diaphragm) Mininum Aperture F16 Minimum Focusing Distance 40cm / 15.7 in. Filter Size (mm) ?77? Maximum Magnifications 1?5.6 Dimensions(Diameter x Length) ?85.4mm ? 99.9mm(3.4 in. x 3.9 in.) Weight 815g / 28.7 oz.