Toronto. In July, 1936 Ernst Leitz in Wetzlar published a free booklet called Lens Tables for use with the Leica Camera. The version I have was produced for and made available from the New York distributor for Leitz products. It explains the optical theory behind depth of focus and its relation to focal length. It also instructed the reader on the concept of hyperfocal distance.
I often used the hyperfocal distance on my Leica M4 lenses to get a maximum range of in focus distance without need to fiddle with settings before shooting.
The little booklet used many tables to simplify the task. Knowing the lens focal length and f/stop, the correct table immediately indicated the sharpest near distance and far distance in feet. The booklet was especially important when using the supplementary lenses alone on the camera or in conjunction with the 1935 BEEOY spider legs accessory which set the closeup framing.