Toronto. As a line from the TV series New Tricks says, this is the last of the Leitz enlarging and copying lenses offered as the film era quietly disappeared.
This is the famous FOCOTAR series (FOCOTAR, FOCOTAR 1, FOCOTAR 2, and WA FOCOTAR). My 1960 version is like new. It is a DOOCQ with a 17675x extension ring to convert it from a copy lens to an enlarging lens. It was bought on April 5, 1987 from the late Bill Belier.
The DOOCQ version of the FOCOTAR was made from 1953 to 1970. It is a beautiful black lens with white lettering and like most non-camera photographic items is short on details.
According to some sources it is a five element optical design with a coating to reduce internal reflections. The FOCOTAR series of special lenses were made in 50mm, 60mm, and 100mm focal lengths at various times and with various code names. At one time the lens was made by Schneider-Kreuznach who made some other lenses for Leitz over the years. I used a 50mm Schneider Componon enlarging lens for many years. I also have a Tele-Arton 240mm lens in a Leica thread. The light Tele-Arton was a favourite of birders and came in various lens mounts.