The Anamophic /i lenses offer superb optical and mechanical performance. SF stands for "Special Flare". The SF lenses have a specially manufactured lens coating that not only gives a more prominent flare but also enhanced bokeh and other aberrations. This gives cinematographers the option for a more vintage, character rich look. Like the S4/i, 5/i and miniS4/i prime lenses, the cam focus mechanism allows for smooth focus adjustments in the Anamorphic /i lenses. Modular construction increases ease of maintenance and serviceability. The Anamorphic /i lenses are designed and made by Cooke Optics to their traditional high standards in Leicester, England and feature an accurate 2X squeeze.