Sun Optical 24-40mm f/3.5 MC Wide Zoom Macro, OM Mount
Sun Optical Co., Ltd (Japan 1950s - 1970s). This is a collectors item, often considered to be the first successful wide angle zoom lens. A bit of play in the focus ring but otherwise excellent condition and works well. A chunky hunk of glass! Size compared here to the OM 40mm f/2 and the Voigtlander 21mm f/4 Color Scopar.