He came up with the Petzval Portrait (modern Austria) in 1840, a four-element lens consisting of a front-cemented achromat and a rear air-spaced achromat that, at f/3.6, was the first wide-aperture portrait lens. Joseph Petzval (of modern Slovakia) was a mathematics professor with no optical physics experience, but, with the aid of several human computers of the Austro-Hungarian army, he took up the challenge of producing a lens fast enough for a daguerreotype portrait. Because of its large flat field over a wide angle of view and its "slow" f/16 aperture (requiring twenty to thirty minutes for outdoor daguerreotype exposures), this lens came to be known as the "French landscape lens" or simply the "landscape lens".īecause the Achromat Landscape lens was quite slow, the French Society for the Encouragement of National Industry offered an international prize in 1840 for a faster one.
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This design was copied by other lens makers. Reversing the lens did increase chromatic aberration, but this fault could be lessened by adjusting the achromat to bring colors at the blue end of the spectrum into focus to match the blue-sensitive nature of the photographic emulsion. The lens had the reverse concave flint glass side facing the subject and an f/16 aperture stop at its radius of curvature, making it reasonably sharp over a wide field of about 50°. īy the end of 1839, Chevalier had created an achromatic version of the meniscus that combined field flattening and chromatic aberration control. Daguerre used this lens in his experiments, but since it was a single-element lens that lacked any chromatic aberration control it was impossible to focus accurately with the blue-sensitive media in the daguerreotype process. Niépce began using Wollaston Meniscus in 1828. In 1812 Wollaston adapted it as a lens for the camera obscura by mounting it with the concave side facing outward with an aperture stop in front of it, making the lens reasonably sharp over a wide field.
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In 1804 William Hyde Wollaston invented a positive meniscus lens for eyeglasses. The Giroux Le Daguerreotype camera used an almost 16-inch (40 cm) focal length reversed achromatic lens with a f/16 stop in front of it made by Chevalier to take 6½×8½ inch (about 16.5×21.5 cm) images. On 22 June 1839, Daguerre contracted Alphonse Giroux (France) to manufacture his daguerreotype apparatus. Reversing the lens caused severe spherical aberration so a narrow aperture stop was necessary in front of the lens. Chevalier reversed the lens (originally designed as a telescope objective) to produce a much flatter image plane and modified the achromat to bring the blue end of the spectrum to a sharper focus. In 1829, Chevalier created an achromatic lens (a two-element lens made from crown glass and flint glass) to cut down on chromatic aberration for Daguerre's experiments.
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Charles Chevalier's Paris optical firm produced lenses for both Niépce and Daguerre for their experiments in photography.