This is a fast f/1.3 50mm Japanese video (TV) lens with c-mount threads for use with Astrovid, Stellacam, and ITE astromonical video cameras most often used to video rich fields, such as Milky Way or medeor showers. See AVA web page for details. Paid $250 from Collins (Makers of I3 intensifier), and it has never been used. I would like to get $200 but will accept any reasonable offer. Many thanks for consideration!