Toronto. In 1958 Leitz Wetzlar began to make and market a new massive focoslide OOZAB (some references list the code name as OOGAN) for its Reprovit series of professional copy stands.
It had a smooth rectangular shape and a new lens thread called the N thread with a 51mm diameter. The new device used the honking big lens mounts the size of big Tuna tins. They were offered in various styles depending on the lens head to be used.
This was the last focoslide (1958-1963) to be made for the screw mount cameras which were quietly disappearing from the scene in the face of the Leica M3 camera series and its popularity. I bought my example from Ron Anger in May of 1981.