On this day in 1879 – March 30th – the German lens maker Bernhard Woldemar Schmidt was born near Tallinn in Estonia.

His name lives on in the Schmidt telescopes. He invented a telescope mirror that let astronomers get sharp wide-field images of the sky with a single exposure. They are still widely used. The best known one is probably the 48-inch Samuel Oschin Telescope at Palomar Observatory, completed in 1948.