The Leica revolutionised the area of photography in so many ways, it is almost difficult to know where to start, so let's just start at the beginning. In 1912 Oskar Barnack, the creator of the Leica, was employed at the Leitz optical company in Wetzlar, Germany, where he was responsible for developing a movie camera. As a 'helper device', they put together a small still-image camera to be used for exposure tests, one that accepted the same cinematic film used in the movie camera.
Luckily, Barnack was also an avid photographer, and he was rather frustrated by the bulk of his 'travel camera', a 13x18cm sheet-film model which required multiple film carriers and a heavy wooden tripod to be brought along whenever he used it. Not surprisingly, he started experimenting with the prototype still-camera from work. Now, the cinema film format was rather small, just 24x18mm, 24mm being the maximum image width on the 35mm film. In the length-direction of the film-strip there were no restrictions however, so Barnack combined the area of two cinema film frames and arrived at the 24x36mm format used ever since.
The camera development was to remain a personal endevour for Barnack for a number of years, he continued his personal use of the prototype and became convinced that producing a camera of that size and construction would be commercially viable.
It took a while to convince the bosses however, after all, Leitz wasn't even a camera manufacturer, they made microscopes and other high-precision optical devices. Finally, in 1923, a small series of prototypes were manufactured for further testing, and the decision was made to take a risk and mass-produce the camera.
The Leica I saw the light of day in 1925, and became a near-instant success, with 57,000 cameras sold. This despite its price-tag which – just like today – was rather high. Leitz had put all their expertise from creating high-precision optical devices into it, resulting in a device capable of yielding superb quality photos. Compared to earlier cameras it was incredibly portable, and by using 36-40 exposure roll-film it was always ready for use. The film-stock was already being mass-produced in large quantities for the movie industry, so supply was not a problem.
The small, portable 35mm camera would go on to revolutionise photography both in the personal and the professional realm. In the world of of photo journalism the 35mm camera really prompted an entirely new era, particularly when it came to war reporting and other conflict situations. It made it possible to carry several cameras with a range of lenses from wide-angle to tele-photo, all while remaining fully mobile.
The first Leica cameras used screw-fit lenses, later a bayonet mount was introduced with the now legendary M series. The story of 35mm photography, which began with Leica, in many ways came full circle in September 2006, when Leica introduced the first digital M Series model, the M8, at Fotokina in Cologne, where the M series made its debut in 1954.