> The modern lens aperture markings of f-numbers in geometric sequence of f/1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45, 64, 90, etc. was standardized in 1949. Previously, this British system competed with the Continental (German) sequence of f/1.1, 1.6, 2.2, 3.2, 4.5, 6.3, 9, 12.5, 18, 25, 36, 50, 71, 100 ratios.
In addition, the Uniform System (U.S., invented UK) sequence of 1, 2, 4, 8, 16, 32, 64, 128, etc. (where U.S. 1 = f/4, U.S. 2 = f/5.6, U.S. 4 = f/8, etc.), was favored by Eastman Kodak early in the twentieth century.