--- "Gordon J. Holtslander" <hol...@duke.usask.ca> wrote: > I'm going to try making some zoneplates. I've read about that zoneplates > require focussing. None of my cameras pinhole cameras can focus. Is > zoneplate focusing necessary in all cases? Is focusing needed only for > subjects that are close to the camera? > > Does it matter whether a positive or negative image of the zone plate is > used? Does the center circle have to be opauque?
Gordon - Like a pinhole, the Zone Plate would be created for a specific focal length. The center does need to be opaque, which then dictates the clear/opaque areas of the surrounding rings. You can reference the excellent article, The Zone Plate by Chris Patton, at http://members.home.net/hmpi/Pinhole/Articles/PinholeArticles.htm for more information. Cheers - george ===== Handmade Photographic Images http://members.home.net/hmpi/ __________________________________________________ Do You Yahoo!? Send your FREE holiday greetings online! http://greetings.yahoo.com
