The Leica I
c. 1913 (Barnack's prototype); 1925 (Leica I shown at the Leipzig fair)
Oskar Barnack's pocket-sized camera used 35mm cine film and a doubled 24 × 36 mm frame. It turned small-negative photography into a serious craft and fixed the format later called full frame.
How it began
Oskar Barnack, an engineer at the Leitz optical works in Wetzlar, suffered from asthma and found heavy plate cameras hard to carry. Around 1913 he built a small camera that took leftover lengths of 35mm cine film, at first to test exposures for movie work. After the First World War, Ernst Leitz II decided to make it, and the Leica went on sale in 1925.
How it works
Barnack ran the film horizontally and doubled the cine frame, which gave a negative of 24 × 36 mm with a 3:2 shape and 36 exposures per load. A sharp lens by Max Berek, designed for small negatives, allowed enlargements to be made. The camera had a focal-plane shutter and a viewfinder; a separate rangefinder helped with focusing.
Why it mattered
Photographers could now carry a camera everywhere, shoot quickly and enlarge the results. Photojournalism and street photography grew up with the Leica and its rivals. The 24 × 36 frame became 135 film, the most popular film format ever, and later the reference size for digital full-frame sensors.
Limits and what replaced it
Users had to cut and load film in the dark, and early bodies lacked a built-in rangefinder. Later Leicas, the Contax and, from 1959, Japanese single-lens reflexes such as the Nikon F built on the format.
Today
Leica still makes cameras in Wetzlar, and its 24 × 36 mm frame is the full-frame standard for digital sensors.