Archived posting to the Leica Users Group, 1998/05/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 03:54 AM 5/6/98 , you wrote: >Paul >Thanks for the rational analysis of my somewhat vague idea. You have >obviously thought this through before, and better, than I did. > >I am, however surprised that you think the lenses would have to be >recomputed. Surely the tolerances are not that tight. Maybe there will be >light falloff on only one corner and a different corner for different >lenses and bodies. Mmm. I think, without actually knowing, that the tolerances really *are* that tight. There are some persuasive reasons to limit the coverage of a lens, most of which have to do with improving contrast and reducing flare. My understanding is that limiting the coverage also makes it possible to improve resolution. Remember, too, that performance generally drops off at the edges of the image circle, so if you go outside the usable image area as designed, the performance might get pretty bad. On the other hand, I note that the lens hood on the 35mm f/2 ASPH actually occludes a portion of the image circle. But this is only wide open, and only on the long side of the negative, and I've no idea what performance would be like at the very edge. - -Paul