Toronto. For many years Leitz made standard lenses for the Leica that focussed as close as a metre. Want to get closer? Too bad. This all changed in around 1927 when Leitz offered supplementary front lenses for its standard 50mm lenses – the Elmar, Hektor and later the Summar.
Leitz offered three lenses to allow close-ups from 39 1/2 inches to 10 1/2 inches. The trio called ELPRO (1*), ELPIK (2*) and ELPET (3*) were sold from about 1927 to 1958. A special ring adapted the tiny marvels to the larger f/2 Summar lens. The ones marked without the * were meant for very early cameras and lenses.
I bought my trio of Elmar supplementary lenses nearly forty years ago from Stan Weyman down in Connecticut and they arrived by mail on January 10, 1980. Leitz went on to make and sell the famous spider legs, extension tubes, focoslides, and other odd focussing mounts that became feasible after interchangeable lenses arrived around 1930.
Many other cameras adopted close-up lenses and they became common place offerings by filter makers as they easily attached with rings or threads meant for filters. Tables and tape-measures were needed to determine the correct focal distance and frame size. This was simplified by spider legs and the other odd gadgets Leitz made and sold.