Soft-focus photographing device
In a soft-focus photography mode, a zone plate section is inserted into a photographing optical path to be set between a front lens and a rear lens. The zone plate section is formed with a central transparent part that functions as a pinhole and a plurality of ring-shaped transparent parts for increasing light amount. Light passed thought the front lens, the zone plate section, and the rear lens falls on a photo film through a shutter that is set at slow speed. In a normal photography mode, the zone plate section retreats from the photographing optical path and the shutter is set at fast speed.
1 . A soft-focus photographing device, comprising:
a photographing lens disposed on a photographing optical path, for forming a subject light image on an image forming plane;
a shutter disposed in said photographing optical path, for controlling light amount of said subject light; and
a zone plate set on said photographing optical path, said zone plate having a central circular transparent part located on a center of said photographing optical path, and either of a plurality of ring-shaped transparent parts with different diameters formed around the central circular transparent part or a plurality of circular transparent parts respectively disposed on a plurality of concentric circles with different diameters.
2 . A soft-focus photographing device according to claim 1 , wherein each of said ring-shaped transparent parts or a total of said circular transparent parts disposed on each concentric circle has nearly the same area as said central circular transparent part.
3 . A soft-focus photographing device according to claim 1 , wherein said zone plate is insertable and removable from said photographing optical path,
further including a photography mode changeover mechanism for selecting either of a soft-focus photography mode or a normal photography mode, said zone plate being set on said photographing optical path in said soft-focus photography mode while retreating from said photographing optical path in said normal photography mode.
4 . A soft-focus photographing device according to claim 3 , wherein said shutter is set at slow speed in said soft-focus photography mode.
5 . A soft-focus photographing device according to claim 3 , wherein said zone plate has a thickness of at most 0.5 mm.
6 . A soft-focus photographing device according to claim 3 , wherein f-number of said photographing lens is greater than f/5.6, further including a photo film having ISO sensitivity of at least 800 disposed in said image forming plane.
7 . A soft-focus photographing device according to claim 6 , wherein said photographing lens has a first lens and a second lens, and wherein said zone plate is disposed between said first lens and said second lens.
8 . A soft-focus photographing device according to claim 7 , wherein said first lens is a meniscus lens.