Archived posting to the Leica Users Group, 1997/05/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hello Otto, >My latest version 35 aspherical is significantly better at f2 than at >f1.4 when I look at just the resolution. Using smaller aperatures does >not improve the resoluton for practical purposes. In practice, my >aspherical delivers top resolution already at f2, and has a higher >resolution at this aperature than the two Summicrons I tried (Well, at >least, the edges are sharper, and the small details easier to make out >when using the aspherical, all other parameters and factors that I could >control being the same). If your ASPH is 'significantly better' at f/2 than at f/1,4 I do not know what you mean by resolution, or how you measured it. On the optical bench and it practical shooting I noticed: (1) the performance of the ASPH is at 1,4 and at 2.0 virtually identical (2) the f/2,0 performance of the Summicron-M and the Summlilux ASPH are the same. You are right as far as the very far edges are concerned. At f/2,0 the ASPH has slightly better performance at the very, very edges (20 mm distance from the center). But the much more important outer zones from 12 to 18mm distance from the center are better represented with the Summicron. Furthermore the ASPH has slightly barrel distortion in the far corners. Resolution is not the only factor when judging the performance of a lens. In balance both lenses perform at f/2,0 admirably, but their fingerprint is a bit different. > >My aspherical has about the same amount of coma at f1.4 and f2 (close to >no coma at all). The two Summicrons I compared the aspherical with >clearly had coma at f2-f4, and gives the aspherical no contest at all. You are right, I did not notice 'coma' myself, nor did I ever mention it in relation to the ASPH. The Viewfinder article is the one that mentioned and showed strong coma at full aperture. BTW, I would like to know how you established the presence of 'coma' at the apertures f/2-f/4 with the Summicron, as this is theoretically almost impossible. Greetings Erwin Puts