Well espoused, Mike. I'll look forward to the write-up with enthusiasm! keith
Mike Johnston wrote: > > > This is an interesting idea: Could the choice of background *and* distance > > from main focus of interest in a photograph be more of an influence than > > lens design in the perception of "bad bokeh"? > > Tim, > In my researches (don't ask), a number of things affect the bokeh: lens > design, aperture shape, aperture setting, focusing distance, distance of the > background objects from the plane of focus, and the contrast, illumination, > and edge texture of the out-of-focus objects. > > IN GENERAL, the worst-case bokeh is found for most lenses a) at wider > apertures, b) closer focusing distances, c) with distant out-of-focus > objects d) when those objects are well illuminated and have high contrast. > > So you can deduce that most lenses to do relatively better when stopped > down, focused farther away, with low-contrast and/or darker objects not so > far in the background. Also, objects with indeterminate or ragged edges will > often appear smoother as long as they're sufficiently o-o-f. You can > actually see this effect in pictures where you may have one hard-edged > object at the same distance as much softer subject matter, like a bright > metal pipe against a muted brick wall or a light-colored streetlight pole > against a mass of foliage. In those cases, where the brick or the foliage > might be perfectly unobtrusive, the harder shape can show more obvious > _ni-sen_ or "double-line" effect. > > I'm going to do a column on Luminous-Landscape about testing lenses for > bokeh, including illustrations that will greatly help clarify the issues, > but it's going to be a lot of work to prepare and I don't know when I'm > going to be able to get around to it. Hope this helps somewhat in the > meantime. > > --Mike
