Archived posting to the Leica Users Group, 2004/05/04
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Karen Nakamura <mail at gpsy dot com> wrote: > OK, am I on drugs or does Leica use two sets of aperture blades? It > seems on many of my lenses, that looking from the front, there is one > set (main set?) that closes down, but from the rear, there's another > set that gradually closes down and catches up at f/22 or so. It's > very odd. > > Is this to smooth out bokeh? Or am I seeing an illusion? Some lenses do have two sets of aperture blades. One I know of is the old 400mm f/5 Telyt. Methinks the purpose is to provide a nicely rounded aperture at all settings - in contrast to the typical auto-diaphragm lenses for SLRs, R lenses included - which degrade to a polygon at smaller apertures. Doug Herr Birdman of Sacramento http://www.wildlightphoto.com