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| Estonian
lens- and mirrormaker who devised a special lens to work in conjunction
with a spherical mirror in a reflecting telescope. The effect of this was
to nullify 'coma', the optical distortion of focus away from the centre
of the image, and thus to bring the entire image into a single focus. Schmidt was born on the island of Naissaar. He lost most of his right arm in a childhood experiment with gunpowder. He studied engineering in Göteborg, Sweden, and at Mittweida in Germany. He stayed in Mittweida making lenses and mirrors for astronomers; in 1905 he made a 40-cm/27-in mirror for the Potsdam Astrophysical Observatory. From 1926 he was attached to the Hamburg Observatory. He worked on the mountings and drives of the telescopes, as well as on their optics. It was in Hamburg that he perfected his lens and built it into the observatory telescope, specifically for use in photography. By replacing the parabolic mirror of a telescope with a spherical one plus his correcting lens, Schmidt could produce an image that was sharply focused at every point (generally on a curved photographic plate, although on later models he used a second lens to compensate for the use of a flat photographic plate). |