Leica's first production camera — the Model A, 35mm scale-focus, cloth focal-plane shutter, 1925.
The Leica I, also called the Model A, was the first commercially produced Leica and the camera that established the 24x36mm frame on 35mm cine film as a serious photographic format. Introduced by Ernst Leitz of Wetzlar in 1925, it was designed by Oskar Barnack and gave rise to the whole Barnack line of screw-mount Leicas that ran for decades.
It is a compact 35mm viewfinder camera with a fixed, non-interchangeable collapsible lens on the early examples and a horizontal-travel cloth focal-plane shutter. There is no built-in rangefinder and no meter; focusing is by scale or by a separate accessory rangefinder in the shoe. Later production adopted the standardised 39mm Leica screw thread, and the shutter is fully mechanical, working without any battery.
As the origin point of the 35mm system it suits collectors and photographers who want a light, quiet, purely mechanical body for scale-focus street and travel work. Handling is spare and deliberate: bottom loading, small controls, and no automation of any kind, which rewards a methodical shooting approach.
When buying, check the cloth shutter curtains for pinholes and capping and test slow speeds for accuracy, as these bodies are very old. Inspect the finder for haze, confirm the film-advance and shutter cocking feel smooth, and verify originality since Model A bodies were sometimes later converted. Bottom-loading condition and body brassing affect collector value more than usability.