Leica facts 14: The Leica 1 model C
The first camera with interchangeable lenses in the Leica catalogue was the Leica 1 model C. Three lenses were available: the 3,5 cm Elmar, the 5 cm Elmar (both with an aperture of 3.5) and the 13,5 cm Elmar with an aperture of 4.5.
The major difference in appearance with the Leica 1 model A is the lack of the hockey stick used for fixing the infinity focus setting.