A short excerpts from "Chevalier Nièpce and Daguerre"pag 52.....It is in this period that Daguerre began to pay visits to the Chevaliers, who had sold him camera obscuras that he needed for his dioramas. The Chevaliers mention to him in conversation that they had heard about experiments that Nicéphore Niépce conducted with a camera obscura. They came to hear about it through Colonel Niépce, who had ordered and purchased a camera obscura with a meniscus prism (8) for Nicéphore, a relative of his, in 1825. Between 1825 and 1829 the Chevaliers supplied Niépce with a series of lenses of various types and focal lengths, which he would need in perfecting his invention. Charles Chevalier will do the same thing with Daguerre beginning in 1832 (10). In an effort to protect the quality of its product, starting in 1830, the Chevalier factory began to glue and mount Achromatic lenses. Charles, who had won a silver medal from the Société d'Encouragement in 1830, and whose ideas were in sharp contrast with his father’s, broke partnership with his father in 1832 and moved the business to 163 di Palais Royal. The laboratory of Vincent di Quai de l’orloge 69 was subsequently bought out by Pierre-Ambroise Richebourg (11). Charles committed himself to the study of microscopes, where he excelled; and more specifically, he developed the research and production of achromatic lenses (2). In 1834 he fine tuned and presented an articulated microscope with a variable lens and prisma radrizzatore at the Exposition des Produits de l'Industrie. The gold medal was given to the invention deemed most remarkable; the judges were both fans of the vertical microscope used in he fields of biology and medicine, and fans of the horizontal microscope used in the camera lucida. He was given another gold medal that year by the Société d'Encouragement....(continues).
pag 71... 1828 Achromat for N. Niépce On 24 March, 1828 the Chevaliers sent N. Niépce the achromat triplet that he had ordered on his return from England. A short letter was attached to the package with two small sketches illustrating how to put the lens together, as the lenses were sent unassembled. From the original drawings, published in Kravets’ book (1949), it can be seen that these were two convergent biconvex lenses that were joined by a divergent biconcave lens. The Chevaliers also indicated which sides of the biconvex lenses were to face the biconcave (35). As it can be seen by the text “Today we have sent you a package with the Regie Poste with an achromat lens of three pieces, a 12 inch focus, 3 inch diameter, with an invoice for the amount of 102 francs. You must be careful to join the surfaces that have been labeled with 0 and 1. Lens A has to face the object and lens C has to face the screen (of ground glass), the three lenses rest on one another with their respective surfaces, as in figure 2. We have done everything possible to satisfy you… Vincent Chevalier pére et fils." But in the end the lens wasn't right for the purpose; being based on the design of telescope, it was essentially more correct at the center than around the borders. ....(continues).