Archived posting to the Leica Users Group, 2003/05/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Thank you Henning. Case closed on this topic. Or should be. Seth LaK 9 - ----- Original Message ----- From: "Henning Wulff" <henningw@archiphoto.com> To: <leica-users@mejac.palo-alto.ca.us> Sent: Saturday, May 17, 2003 7:44 PM Subject: Re: [Leica] Vignetting of Summicron M 2/28mm ASPH > At 7:16 PM -0400 5/17/03, Don Dory wrote: > >Phong, > >I was implying that if an element was moved out of it's designated location > >+/-0.003 then bad things happen to the light. The designs coming out of > >Solms are fabulous, but there are continuing occasional tales of really bad > >results, sometimes flare, sometimes severe vignetting, sometimes not as > >crisp as supposed to be. The only logical conclusions would be either an > >element out of spec or an element out of place. > > > >The +/- comes from one of Erwins bulletins when he was talking about the new > >retro 50 and how it conforms to muck tighter specs than the other 50 > >Summicrons he has tested recently. > > > >Thanks for reading. > > > >Don > >dorysrus@mindspring.com > > As I have stated numerous times, vignetting by the lens is not a QC > issue, but is an intrinsic part of the lens design and construction. > +/-0.003 anything except meters or leagues will have no effect. > Decentering, which I assume you refer to, has serious effects on a > number of aberrations but not vignetting. Besides, centering has > generally been one of the strong suites of Leica, and they continue > to be at the forefront in this regard. The QC problems relating to > missed edge blacking and other things has nothing to do with this. > > As someone else has pointed out, if Y.Li has consistently greater > light falloff on one side of the frame than the other, he has a > shutter, not a lens problem. > > If the images are sharp, and from what Y.Li has written this seems to > be the case, decentering is not an issue. The issue is that he, and > seemingly others on this list do not understand what parameters are > affected by the intrinsic optical designs that Leica employs for > their wideangles, namely standard or very slightly retrofocus > construction versus the exteme retrofocus construction used by > designers of SLR lenses. Different people have different expectations > of a lens, and will put up with or vilify a lens for different > properties. I hate distortion; Y. Li seems to hate any vignetting. I > can easily fix vignetting in printing or with a center filter, but > cannot reasonably fix distortion, so my criteria are plain. > > Again, read my previous posts on this topic. > > -- > * Henning J. Wulff > /|\ Wulff Photography & Design > /###\ mailto:henningw@archiphoto.com > |[ ]| http://www.archiphoto.com > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html