Toronto. When the Leica hit the market in 1924, it used a miniature focal plane shutter that was self capping.There are two curtains. The first moves across in front of the film followed by the second. The delay between the two events determines the shutter speed. On rewind, the first and second curtains lock together keeping light from hitting the film.
Here you can see my Exakta after I had disassembled it to see why the speed test shots were so wavy. A brass stop was nearly worn through and the grease on the second shutter curtain column had dried out (this caused erratic shutter cloth movement and a wavy image on the film – the damaged brass stop meant the camera could no longer be safely used).
The FP shutter actually saved manufacturing costs since one shutter worked with all lenses. Leaf shutters were usually imbedded in the lens meaning each lens had to have its own shutter. Alternatively, the shutter was placed at the back or front of the lens, or only the front elements were exchanged.