Sigma 100-400mm F5-6.3 Contemporary DG OS HSM Lens for Canon with SD Card BundleBlending a long reach with a convenient form factor, the Canon EF mount 100 400mm f 5 6. 3 DG OS HSM Lens is a telephoto zoom lens within Sigma's Contemporary series that blends both a refined optical design with a compact and lightweight physical construction. On the optical front, this zoom utilizes four SLD glass elements to noticeably reduce chromatic aberrations and color fringing throughout the zoom range for improved clarity and color accuracy,