For treating the surface of the bayonet, the part which connects an interchangeable lens to the camera, hexavalent chromium is the most commonly used material. At SIGMA, however, we instead opt for trivalent chromium, which is both more environmentally-friendly and safer. Compared to hexavalent chromium, the trivalent chromium we use is a more costly material, more difficult to process and manage, but it enables us to create products with improved quality and performance with a reduced environmental impact.
photo : Motonobu Okada
lens：SIGMA APO 70-200mm F2.8 EX DG OS HSM
SIGMA Aizu factory, Surface Treatment Section, Assistant Manager
While dust prevention, protection against corrosion as well as a high aesthetic value are obvious goals of surface treatment, other vital effects include improving material capabilities (for better wear-and-tear) and mechanical qualities (electrical conductivity, hardness, lubrication etc.). As the key component in providing a stable connection with the camera, a good bayonet is the cornerstone of an interchangeable lens.