A zone plate is a body cap for a single lens reflex camera through which a small hole has been drilled. Adhered to the underside is a series of concentric circles rendered from a material which creates a fresnel thereby diffracting and diffusing the light as it hits the camera sensor. The images are soft and diffuse, with an ethereal glow. A zone plate body cap is placed on an SLR (digital or film) in lieu of a lens. There is nothing to focus as there is no lens; just set the camera to aperture priority and it will figure out the appropriate shutter speed. Similar to a pinhole body cap, the zone plate hole is a little larger which allows you to view and compose your image through the viewfinder. For more information see www.pinholeresource.com.