Das Auge der Welt (1935)

This film explains in a generally understandable form how television works. It also shows the first true videophone system, with two-way video and two-way audio invented in the Third Reich. Germany's videophone system was quite impressive of an invention for it's time. Video was delivered at 25 frames per second on a cathode ray tube display. It's resolution of 172 rows, which made for a pixel count of about 40,000, is said to have been enough for one to discern the hands on a wristwatch.

The first 2-way videophone service was launched on March 1, 1936. It was provided in Germany by the national post office and connected Berlin with Leipzig. Some 100 miles of broadband coaxial cable were used to deliver video calls between the two cities. Later on, the service was opened to the public, and additional lines connecting other major cities were added.

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