The emergence of optical calculators in the 1950s intensified the quest for ways to construct high-speed lenses with satisfactory open-aperture performance. Doubling the light transmission by widening the aperture from f/2 to f/1.4 in fact quadruples the aberration rate for which the lens must compensate.
In 1959, Leica introduced the Summilux 50 mm f/1.4 – the first-ever model of the Summilux series. Based on the Summarit 50 mm f/1.5 (launched in 1949), the new lens featured different lens diameters as well as new glass types developed in the Leitz laboratory. The glass, in turn, was a refined version of the Xenon 50 mm f/1.5 (launched in 1936), now improved with an anti-reflective coating.
Aided by this array of new technological innovations, the lens offered noticably better image quality. However, just two years later the design of the Summilux 50 mm f/1.4 was outdated – making its production run the shortest of any Leica lens.
Leica's departure from the Summarit series by naming their new lens 'Summilux' may have had two reasons: for one, the Summilux 50 mm f/1.4 was closer in kind to the Summicron 50 mm f/2, launched just a few years earlier. In addition, the term 'lux' refers to the lense's capability for 'increased light'.