Piesker Berlin Tele-Picon 250mm f5.5
M42 / PL
Piesker was an obscure Berlin optical company, that specialized in long lenses. For some reason there were several such long-lens companies in Berlin - Astro-Berlin, Tewe, Piesker, Astragon(which may be a trade-name of Astro). Piesker seems to have produced a single set of mainly long-lens/telephoto preset designs in the 1950's, and then closed in the early 1960's.