Atelier Bonryu(E)
zone plate photography
Gallery: Zone Plate Photographs
Moon and Flowers
Except for a special case it is rather difficult to take an astronomical photograph by a lensless camera because less light is concentrated by a lensless camera in comparison with a camera with a lens. Therefore, a lensless camera can be used to take a photograph of an extremely bright object such as the sun. Then, is a lensless camera useless for taking a photograph of a darker astronomical object? The truth is that usefulness of the lensless photography is pointed out since long ago. Lensless photography of X-ray, gamma ray, or short wave length ultraviolet light is already in practical use. By utilizing the lightness of a zone plate a dreamy project to construct a gigantic space telescope is considered as described in Salon of zone plate photography. As for astronomical use of zone plate by an amateur astronomers/photographers P.C. Slansky succeeded to take a photograph of the venus by a zone plate telescope of f= 4 m.
Generally it is believed that zone plate photographs are softer and more blurred in comparison with pinhole photographs. However, it is not necessarily true as described in the Salon. Though higher resolving power of the zone plate is attained by increasing the number of zones, the width of the outermost zone becomes narrow with increasing the number of zones, which limits the number of zones from the technical viewpoint. This problem is solved by increasing the focal length. It seems advantageous to increase the focal length because the magnifying power is also increased by increasing the focal length. However, a zone plate with a long focal length brings other difficult problems. Firstly, a tough and highly accurate stand is required for a long focal length telescope. And secondly, the chromatic aberration becomes severer for a longer focal length zone plate.
The following pictures are photographs of the moon and flowers by a long focal length zone plate. The focal length and the number of zones of the used zone plate are 300 mm and 65, and the corresponding range of the light wavelength is very narrow (540 - 560 nm). In spite of the narrowness of the permissible range of wavelength color of a flower seems unforced as shown in the following photographs. This is probably because the depth of focus becomes deep for the object at the finite distance and lights with the wide range of wavelength can be focused. Though the wavelength range of the band pass filter BPB55 is almost the same with the zone plate, a zone plate photograph of the moon taken by using this filter seems quite different.
#5A: f=300 mm, 65 zones, E-300, #5B: f=300 mm, 65 zones, E-510
(Slide show)
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(English Edition)
Complete Guide to
Zone Plate
Photography
Lensless Photography by Rings of Light
Volume of
Stones
Volume of
Birds
Volume of
Flowers
