Sigma 50mm F1.4 DG HSM Art Lens for Canon Cameras Redesigned, Reengineered, Revitalized The staple Sigma 50mm 1.4 DG HSM has been redesigned and re-engineered 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 auto-focusing 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. Dimensions (Diameter x Length): 85.4 x 99.9mm / 3.4 x 3.9 inches. Weight: 815 grams / 28.7 ounces. USB Dock Compatibility Sigma has developed special software (SIGMA Optimization Pro) that can update the lens firmware and adjust parameters such as focus. About Sigma Since 1961, and with the recent introduction of Sigma Global Vision, we have worked toward one single, simple goal: To hold ourselves to the highest standard of design and manufacturing of imaging products. Photography is all we do. And it's all we've done. So you can rest assured that it's something we know extensively and care deeply about. You have a vision. We've made it our mission.