ZENTMAYER WIDE-ANGLE LENS
Joseph Zentmayer, Philadelphia, Pennsylvania Mid-1860's - Early 1880's
This globe-style lens design was patented by Joseph Zentmayer on May 29, 1866, under Patent No. 55,195 for a "Combination of Lenses for Photographic Purposes". In Zentmayer's own words taken from the patent:
"The nature of my invention consists in arranging a doublet of meniscus lenses of different curvatures but with their exterior surfaces concentric, the lens with the longest radius being used as the front lens of the combination; then in using the front lens of such a combination as the back lens in combination with one of still longer focus or radius to form an instrument of larger size or longer focus."
Coming to America from Germany, Zentmayer established his own shop in Philadelphia in 1853, building microscopes and other optical apparatus. Zentmayer manufactured this doublet style wide-angle lens, beginning in the latter 1860's, with advertisements found for his lenses through at least 1882. This example features a rotating aperture (or wheel stop), with the 1866 patent date engraved on it alongside Zentmayer's name. A simple (but effective) shutter was incorporated, consisting of a sliding bar with a single blade at the end. When pushed inward, the blade blocked the light from entering, thus eliminating the need for a lens cap.
By the mid-1870's wide-angle designs by Richard Morrison and other lens makers had taken hold, and the popularity of Zentmayer's lenses began to decline. Despite having been manufactured for a number of years, production was relatively low given the few lenses that survive.
Joseph Zentmayer was well known for his microscopes and telescopes, and the build quality of this lens is exceptional. His products were highly regarded during his lifetime, and continue to be, among collectors today.
U.S. Patent and Trademark Office
Shutter rod set in the open position