Archived posting to the Leica Users Group, 2000/11/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> In light of the recent exchange over the "science" of out-of-focus and > bokeh, has anyone read the following from Harold Merlinger? > > got to: > http://fox.nstn.ca/~hmmerk/HMArtls.html#anchor26001 > > then download this file: > ATVB.pdf > > What about this? > Interesting reading I think. > > Henry Ambrose > who when it comes to bokeh, calls it "moosh" Very interesting thread especially for a european. It is a new notion for me. Pictures I saw show a great analogy with the classical star test in optical astronomy. Intra and extra focal images of a star show patterns very similar to these I saw in enlarged pictures of small brilliant areas: a relatively dark area surrounded by a brilliant ring. The patterns in enlarged pictures are clearly an envelop of some individual diffraction figures. In astronomical optics, the symmetry between intra and extra focal patterns is a very sensitive way to say if an optical element is well corrected in regard of spherical aberration. A pinpoint star at focus, and a good symmetry between intra and extra focal planes say that an optic is perfect. I think that bokeh could be exploited to achieve an actual optical test for photographic objectives. Imagine a flat black plane with many steel brillant balls, like these of roller bearings. A flash lightning the scene would produce a pretty fine punctual source on each ball. Focusing in the middle of the plane would produce many intra and extra focal patterns, and focused images would be very thin. Probably a hard test for many optics... JMB