Zone Plate Body Caps
A zone plate body cap is a device used in the place of a lens. Unlike lenses however, zone plates use diffraction instead of refraction, they are sometimes called Fresnel zone plates. The zone plate's focusing ability is an extension of the Arago spot phenomenon caused by diffraction from an opaque disc.
Zone plates are also used in photography in place of a lens or pinhole for a glowing, soft-focus image. One advantage over pinholes (aside from the unique, fuzzy look achieved with zone plates) is that the transparent area is larger than that of a comparable pinhole. The result is that the effective f-number of a zone plate is lower than for the corresponding pinhole and the exposure time can be decreased.
Zone plates are also used in photography in place of a lens or pinhole for a glowing, soft-focus image. One advantage over pinholes (aside from the unique, fuzzy look achieved with zone plates) is that the transparent area is larger than that of a comparable pinhole. The result is that the effective f-number of a zone plate is lower than for the corresponding pinhole and the exposure time can be decreased.
Can produce some very nice and dreamy photos with this process, just A Whole New Way To Enoy Photography.
