The earliest Leica prototypes were developed by the company Ernst Leitz during the first years of the 20th century, but marketing did not commence until the mid 1920s. The Leicas were innovative, by orienting the image frame sideways for the 35 mm film as opposed to the cine-camera tradition of across the film-strip. The cameras were compact with collapsible lenses, for hiking and biking. The rangefinder feature was added with the Leica II during 1932, and that year both rangefinder and viewfinder cameras became available with interchangeable lenses. In 1933 the Leica III offered slow-speed shutter controls and a fast 1/1000th shutter speed, and various iterations of the III (a,b,c,d,f,&g) series became the flagship models and best sellers into the late 1950s. Further iterations of the models I and II were offered, but did not sell well.
Prior to WWII Leica and competing Contax cameras from Zeiss Ikon were considered to be the finest 35mm cameras, but post-WWII the companies had competition from Soviet and Japanese copies. During the 1950s Japanese quality and innovation, along with low pricing, devastated the European camera industry. Leica became an expensive type of camera bought largely by professional or serious photographers. However, the advent of reflex camera technology made rangefinders somewhat obsolete, leaving Leica the main product of a diminishing market segment. Leica has remained a notable trade-name into the 21st Century.
The original producer of the cameras, Ernst Leitz GmbH, is now three companies: Leica Camera AG, Leica Geosystems AG, and Leica Microsystems GmbH, which manufacture cameras, geosurvey equipment, and microscopes, respectively. Leica Microsystems GmbH owns the Leica brand and licenses its use by the other two companies.

LEITZ THALIA series lenses

LEITZ THALIA