Premium Compact Primes"" for mirrorless usersThe Sigma I series features full-frame compatible lenses that offer new value to mirrorless systems. The combination of superb optical performance with a level of compactness that is perfectly suited to smaller and lighter modern mirrorless cameras will bring you new opportunities for a perfect shot. Sigma is aware that in today's world we have a wide range of camera choices, especially with the increase in mobile phone ownership.But with many people look for something more than a mere act of ""taking pictures"" when they choose to own a camera and lenses, I series lenses offer the ultimate combination of superb optical performance, outstanding usability and compact form-factor. Sigma's excellence in development and production technologies has been built up since our founding in 1961 and became increasingly sophisticated with the introduction of the Sigma Global Vision brand in 2012. With this as a base, Sigma has given careful thought to the quality of the products, the feeling of using it and the pleasure of owning it. This is how the I series was born.New standards of optical performance for the Contemporary lineThe 65mm F2 Dg | Contemporary brings to the table the highest level of optical performance at a maximum aperture of F2 with a lens body of a size that matches a mirrorless system.Axial chromatic aberration, which tends to be noticeable with medium and telephoto lenses and cannot be effectively reduced in-camera, is corrected thoroughly with the use of Sld glass, allowing it to capture sharp details. A pair of glass-molded aspherical lenses is used to correct spherical and comatic aberration, as well as astigmatism, while also helping make the lens configuration smaller in size. A combination of the latest optical design with advanced processing technology that brings life to the former gives the 65mm F2 Dg | Contemporary its excellent optical performance as well as compact size.In addition to the beautiful bokeh effect thanks to the control of spherical aberration, the reduced vignetting effects help curb lemon-shaped or swirly bokeh and give photographers greater control over the out of focus areas of their images. On top of it all, the Sigma-standard anti-ghosting and anti-flare technology ensures high-end performance in backlit conditions.Use of multiple high-precision aspherical glass molded lensesThe surface of molds for glass molding, which is a process that forms optical components by pressing glass materials at high temperatures, requires ultra-high precision. Sigma uses high-precision molds whose surfaces are controlled with an accuracy of +/-5 nanometers (0.000005 mm) or smaller. High precision aspherical glass molded lenses archives both good aberration correction and compact lens size.Exceptional I series build quality with a compact form-factorAll I series lenses have an all-metal construction. The precision-cut aluminum parts not only give the barrel a sleek, stylish finish, but provide superb durability, which improves the quality of the entire product. Metal materials are also used in internal structures that slide with the operation ring for added robustness.