Bundle Includes: Sigma 24-70mm f/2.8 DG OS HSM ART Lens for Canon EF USB Dock for Canon Lenses Camera System Gadget Bag with Accessory and Cleaning Kit and 2 x 64GB Extreme PRO 200MB/s SDXC UHS-I Memory Card Constant Aperture OF F/2.8: A constant aperture of f/2.8 through the zoom range makes this a highly versatile tool and a brand new Optical Stabilization (OS) system helps compensate for camera shake. Though a common focal length the Sigma 24-70mm Art brings a new level of usability and durability featuring a rugged metal barrel and an emphasis on image quality Outstanding Optical Performance: Three SLD (Special Low Dispersion) glass lens elements and four aspherical lens elements minimize optical aberrations. To ensure outstanding edge-to-edge image quality the optical system minimizes coma which causes points of light to streak and transverse chromatic aberration which cannot be corrected via aperture control. The optical system also minimizes distortion which can be