Why Metabones Since its inception, Metabones has been designing and manufacturing lens adapters recognized among professionals and enthusiasts as leaders in design and workmanship.Contrary to the popular trend of other factories using an aluminum ring painted black on the camera-body-side, we instead take no short-cut but use precision-machined brass with chromium plating on both the camera-body and the lens sides of our adapters, in order to ensure smooth mounting, great appearance, and durability. The lens side of the adapter features a strong leaf-spring structure, strengthening the adapter-lens connection and ensuring tightness of the lens in order to reduce wear and prevent focus errors and optical alignment issues from appearing.Metabones uses matte-black treatment to keep internal reflection to a minimum in order to maintain the maximum optical quality possible with the lens.All Metabones Adapters follow this tradition of uncompromising precision, robust build quality and outstanding finish.