The Formula 5 MC 135mm f/2.8 is a telephoto prime lens for 35 mm SLR cameras with the M42 screw mount.
This is rather a rare telephoto lens. It is difficult to find any information both on the lens and its manufacturer. It was presumably produced by Eyemik Mitake Optical Co Ltd (Mitake). The lens features a very pleasing build without plays and quite smooth travel of the focus ring. It delivers soft images when wide open, but from f/4 onwards it is already rather sharp.