In what ways, if any does refraction affect this as the lens is stopped down? This distribution of energy must give individual lenses their signature bokeh then, no? I'm trying to get a grasp on this... Health, Peace Lance Selma, NC 27576 ~~~~~~~~~~~~~~~~~~~~~~~ In a message dated 11/8/2007 8:40:22 PM Eastern Standard Time, egoldste@xxxxxxxxx writes: There used to be illustrations of this on the web but I am not finding them now. Essentially, a lens can either be designed to draw the energy of the point as distributed as a concentrated central point with a light, airy disc of lesser energy surrounding it, or a light airy central disc with a more concentrated ring of energy surrounding it on the periphery. One yields higher resolution, the other higher edge contrast/accutance... But the notion is that it is the distribution of energy around how the lens draws a point of light which accounts for the difference... Eric Goldstein -- On 11/8/07, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote: (snipped) > If one charts the energy distribution of a beam of > light focused by the lens one finds that the high contrast > lens concentrates the light in a small beam or spot but has > many smaller peaks or beams surrounding the main beam. These > cause a sort of flare around the main beam lowering the > contrast. By suitable adjustment these secondary beams can > be much reduced at the cost of making the main beam broader. > The second condition reduces the resolution but increases > the contrast. The process is known as apodisation or removal > of the feet. For those familiar with radio antennas or > acoustic radiators an exactly analagous condition exists > there, the suppression of minor lobes with the concurrent > broadening of the main lobe. --- Rollei List ************************************** See what's new at http://www.aol.com