Archived posting to the Leica Users Group, 2001/08/03
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]on 8/4/01 12:13 AM, Erwin Puts at imxputs@ision.nl wrote: > There has been some discussion on this list about the image quality that can > be attained with a pinhole camera. > >>> A properly-sized pinhole should be able to beat any Leica lens, too, as long >>> as exposure times are not an issue. >>> >> That is utter rubbish. You prove your ignorance every time you post. >> Congratulations. >> >> Jimmy is of course quite right. Will Msxmanic admit his diffraction-limited >> error? I can't wait. Over on Streetphoto he recently admitted he DIDN'T KNOW >> something, so anything is possible. [SNIP] > Anthony commented on pinhole quality and some typical responses are quoted > above. One of the reasons for me to stay out of discussions as long as > possible is the agressive tone and low quality of many exchanges of opinion. > But before proving/stating some persons ignorance one might want to look up > the facts in an optical handbook. While Anthony's statement is not exactly > true, there is more value in it that the commenters want to belive. A pinhole > camera, with a properly measured diameter of the pinhole will give you > distortion free architectural pictures of great depth of field and very > commendable reproduction of shapes and even details. Of course the edges of > the pinhole will generate diffraction but I wonder if it is more than that > what you would get when stopping down a lens to f/16. curiously, Erwin omits to quote my post referring to a detailed examination of pinhole optics, including a experimental and theoretical limit to their sharpness. In particular, his statement that pinhole diffraction may not be more than you get in a lens at f/16 is deeply strange. The whole point about pinhole optics is that diffraction effects ARE the limiting factor... at a certain point making the pinhole smaller doesn't make the image sharper because diffraction effects set in. Unfortunately, the image formed by a pinhole at this point is not a nice sharp one like a lens at f/16, but a fuzzy one because the pinhole isn't small enough to render details sharply. And making it smaller justs makes matters worse. Tests with pinholes of optimum diameter at their optimum focal distance clearly show a resolution an order of magnitude less than standard optical lenses. I would be astounded if anyone had ever made a pinhole that could resolve 10 lp/mm. > So before you hang a man at the willows, do your home work. Well I did, Erwin, but I wonder if you did? All someone has to do is produce a sharp pinhole photograph to end this discussion right now. Don't hold your breath. - -- John Brownlow http://www.pinkheadedbug.com ICQ: 109343205