A very well built all-metal lens which would last a lifetime. Manufactured by Zenit in their Kragnogorsk factory in Russia. The Russians are renowned for their optic capabilities and this multi-coated lens is no exception. Being a 500mm mirror lens, it has a fixed aperture of F8, allowing for very sharp pictures indeed. Supplied in a wooden case with 4 colour filters and a 2X converter. On a Canon DSLR camera with the 2x converter, this would equate to 1600mm, 1500mm on Nikon, Minolta and Pentax DSLR's, and 1700mm on the Sigma DSLR cameras.