Toronto. The Leica was marketed in 1925, catching Zeiss off guard. It responded in 1932 with the Zeiss-Ikon Contax. It had to better the Leica in every way possible: faster lenses, vertical shutter (faster curtains), metal shutter, longer rangefinder base, wider range of lenses (Leica had interchangeable lenses and a rangefinder by then), and so on. Unfortunately it was more expensive to make and the metal shutter while seemingly better, was its achilles heel over time. The brass in the shutter strips crystallized while the enclosed silk ribbon wore out causing the shutter to drag, Details of Zeiss are shown in the Zeiss and Photography book by Larry Gubas, and in the publications of Zeiss Historica Society.
In the 1920s, the head of Zeiss optics, Willy Merté, designed the world famous f/2, 50mm Biotar. I saw one in the late 1950s on an Exakta. For that camera, it was an f/2, 58mm design that unlike the kine and rangefinder versions may have needed the longer focal length or even a slightly modified retrofocus design to accommodate the SLR’s mirror. The non mirror cameras focussed infinity closer (distance from the diaphragm to film-plane) and had no need to clear the mirror so the original double Gauss design worked without difficulty.
On September 7th, 1928, the original design (100mm focal length in two versions, a 7 element and a 6 element) was submitted to the USPO and patent 1786916 was approved and issued on December 30, 1930. Under the Zeiss licensing process, the Bausch and Lomb BALTAR was manufactured in Rochester using that patent. The lenses came in various focal lengths for 35mm cine cameras used by Hollywood for major motion pictures. My version of the BALTAR has coated lens elements indicating it was made post -war (coatings were not readily available until after 1945). LED reflections suggest that it is the seven element version.