Archived posting to the Leica Users Group, 1997/11/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>'Bokeh' falls in this >catagory: it has no sound scientific, not even factual basis. It is >'believer-stuff'. Like Ronald Reagans SDI project: it is easy to talk >about, we all seem to agree, no one has ever seen it and in never actually >existed. For an extreme example, start by comparing photos taken with a mirror lens to photos taken with a regular long-focus lens of the same focal length, and see if you can tell which lens took each one. Then decide if out-of-focus donuts (or the lack of them) contribute to the subjective quality of the image. If you see a difference, you're reacting to the difference in bokeh. Just look! Some lenses produce very soft out-of-focus areas with a lot of detail in them, and a soft transition from sharp to unsharp. Others produce blocky-looking out-of-focus images, which look almost like abstract paintings, with a sharp transition. Look at photos taken in the 1920s and 1930s, at that strange sharp-yet-not-sharp look that many close-up portraits have. You can't duplicate that effect with a soft focus filter. These are all differences in how lenses render bokeh. As for there being no sound scientific basis, certain characteristics are well known--for instance, lenses that are highly corrected for spherical aberation tend to produce a double image in the out of focus areas; you can especially see this in edges and highlights. I knew of this before I ever heard of bokeh. I don't think that this is something to worry about and fuss over, but you can see it and it is real. On the other hand, good "bokeh" will not save a lousy photo, and a strong photo will survive awful bokeh. - - Paul