The Teleros is a telephoto lens made by Ross of London. It was introduced in 1922, and replaced the Telecentric. It was made until at least 1938. It was made in a wide range of focal lengths, from a 4-inch Leica-fitting lens to a 40-inch lens intended for 8½x6½ inch plate cameras. It was available as an f/5.5 with magnification of two (i.e. the back-focus is one half of the focal length) or an f/6.3 with a magnification of three.