Archived posting to the Leica Users Group, 2000/01/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Mark Rabiner wrote: > John Collier wrote: > > > > on 21/1/00 8:28 pm, Jacques Bilinski at jbilin@axionet.com wrote: > > > > > I've read statements to the effect "I don't take pictures of documents, etc. > > > I take pictures in the 3 D world. Therefore flatness of field doesn't matter > > > to me" a few times on this list. Is there any valid logic to this? > > > > > Well the fact you read it on this list should answer your question ;-) > > > > John Collier > > I am also confused by these issues. A macro lens is designed for field flatness, > a non macro is not. This is undoubtedly something else. > Mark Rabiner Mark, Flatness of field has really nothing to do with macro or not macro. Flatness of field is really not flatness of field at all, it is really some artificial bending of the light rays which is not present in a normal lens. A normal lens just does what nature intended it to do. We humans did not like this and changed its characteristics to please us. This change enables us to run the film in our cameras in a flat plain . Else we would have to have the film plane curved to accommodate an uncorrected lens. If you take a picture of uncle bill, then his legs are at a further distance from the lens, than his chest. Under normal circumstances, the focal point from the rays of the chest, would be at the film plane (in the middle if the picture) but the legs would be some distance in front of the film plane (at the upper edge of the picture) .Now that would never do. Imagine, uncle Bill with fuzzy feed). Unthinkable. Therefore the field is flattened to accommodate the straight plane of the film. Most the old Petzval type lenses used for movie projection had a film flattener. this was another meniscus lens very close to the film. Regards, Horst Schmidt