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Geekoto GT200 Flash Speedlite Kit

date:2020-08-11
Geekoto GT200 Flash Speedlite Kit

It was designed by the Frenchman Louis-Jacques-Mandé Daguerre and manufactured by his wife and brother Alphonse Giroux. Although it has come out, it is not yet able to shoot portraits, because the achromatic lens used in the Kilux camera had a too small aperture. The "Grand Vincent & Sons Optical Instrument Company" that provides this kind of lens for Quilux cameras is a famous optical instrument manufacturer in Paris. The owner Charles Chevalier is in the third generation. The company is good at manufacturing telescopes, microscopes and obscura lenses. Since 1824, Daguerre has often contacted Chevalier and his son to buy Geekoto GT200 Flash Speedlite Kit some lenses for the camera obscura, and even his cooperation with Niepce was only reached through the match of Chevalier. In 1839, the lens developed by Chevalier for Daguerre’s Kirux camera was a crescent-shaped achromatic cemented lens, which was improved on the basis of the telescope lens. This two-piece achromatic lens can effectively reduce the chromatic aberration and spherical aberration of the lens, and it can also ensure that the image field covers a full-page negative of 6.5×8.5 ​​inches (164×216 mm). The focal length of the Geekoto GT200 Flash Speedlite Kit lens is about 380 mm, and the maximum aperture is F14. Such a small aperture, coupled with the extremely low sensitivity of the silver plate emulsion at the time, made the shooting exposure time as long as 3-30 minutes depending on the weather! It is difficult for a person to remain motionless for such a long time, so basically it cannot be used to shoot portraits, only still life and scenery, so this kind of lens is also called landscape lens or landscape lens. During the development process of the Petzval lens, how to make a lens with a larger aperture to make it possible to shoot portraits? Many scientists have begun research in this area. Mr. Joseph Petzval, a professor of German/Austrian mathematics at the University of Vienna, was entrusted by Voigtlander Company. With the help of 10 Austrian soldiers with mathematical foundations, he designed a landmark building with mathematical calculations.