Archived posting to the Leica Users Group, 2010/09/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The early ones already have rare-earth glass it weems: Correspondence betweeh Steve Gandy and MODERN Photography I believe the lens you're talking about is the rigid Summicron lens made from 1953 to 1956 and having 4 of its 7 elements made from lanthanum glass, a rare earth glass. I wrote to Leitz in Rockleigh, NJ about the 7 element Rigid Summicron to found out more information. They replied that the Rigid and Dual Range 50/2 Summicrons are exactly the same, the only difference being the mount. My question: Is the Dual Range the same lens and glass? If it is the same lens why does it not rate the same as the rigid lens? Is there anything wrong with the Dual Range 50 mm /2" Modern's reply: "First of all, both the 50/mm f/2 Dual Range Summicron and the "plain" rigid 50 mm f/2 Summicron are essentially the same 7-element lens, with rare earth glass elements as you state. The only important difference is the focusing helical, which gets you down to 19 in with the former and 3 ft, 4" with the latter. Both versions can accurately be described as "rigid 50 mm f/2 Summicrons" as neither is collapsible. Your assumption that we were somehow slighting the Dual Range Version is therefore unfounded. As a mater of fact, the actual lens which topped Modern's 50 mm lens test list happened to be a Dual Range Summicron, through the 7-element non-close-focusing version provides, on average, identical performance." At 11:23 AM 9/24/2010, you wrote: >Any information out there about the rare-earth Summicrons? > >If I recall correctly, they were all made in collapsible mounts but if >there was a rigid version ever made, I'd love to find one. > >Alternatively, I could have a collapsible collimated to a digital >sensor and "locked" in the out position somehow to ensure that it kept >its proper registration. > >I only mention the rare-earth lens because one of my favorites is the >SMC Takumar 50mm f/1.4 with rare earth elements. It's fantastic when >not fogged. That lens is the reason that I always want to keep a >Spotmatic around. > >I've pondered long and hard on how to get that lens properly focusing >on a Leica, be it with transfer of the optical cells or an adapter with >RF coupling. > >Phil Forrest > > >On Fri, 24 Sep 2010 11:01:57 -0400 >Chris Saganich <chs2018 at med.cornell.edu> wrote: > > > Thanks Seth, that confirms what I seem to have been seeing as the > > major difference between my DR (your former DR btw) and the later > > 50's I have. The later 50''s worked very well for long exposure work > > where I exposed up to 45 seconds at f2. Here is one example: > > > > > http://www.imagebrooklyn.com/Portfolio/Williamsburg%20Portfolio/Williamsburg%20page%201.htm > > > > As you mentioned when I used the DR for this sort of work the > > difference was obvious. > > > > At 03:36 PM 9/23/2010, you wrote: > > >Scanning the batched conversations I came across this one that > > >caught my eye and about which I have some significant knowledge. > > >Some on the list may recall my writings in LHSA's Viewfinder > > >magazine several years ago contradicting Erwin Puts' statements > > >about the series of 50/2 Summicrons. One of them even resulted in > > >marc small accusing me of libel and predicting that Erwin would sue > > >me. Poor lawyering on marc's part as truth is an absolute defense to > > >a defamation action. ;-) > > > > > > > > > > > >My purpose here is to dispel a very widely held opinion that the 1956 > > >DR/Rigid 50 Summicron is a low-contrast lens. It is not, except when > > >compared to the latest Leica and other lenses at wider apertures. > > >Ten years ago I had correspondence with Lothar Koelsch, then head of > > >lens design at Leica, about this very issue and received from him > > >print-outs that I have in my hands as I write, of the MTF curves > > >calculated by Leitz/Leica Camera, for the 50/2 lenses from the > > >Summitar through the DR/Rigid, 11817 (1969) and the 1979 version > > >that I believe is still current. > > > > > > > > > > > >Bear in mind that every lens is a compromise, that there is no such > > >thing as a perfect lens. If there were, such a lens would perform > > >flawlessly at full aperture and as a photographer stopped down, the > > >image would degrade progressively because of diffraction! So the > > >designer has to decide in which direction he/she wishes to correct > > >for most, since one cannot correct all aberrations simultaneously. > > >The DR/Rigid concedes some softening contrast at f/2 and 2,8 in > > >order to correct more highly for spherical and chromatic aberrations > > >and thus achieve significantly higher resolution. Geoffrey Crawley, > > >then Editor-in-chief of the British Journal of Photography, > > >confirmed to me in our correspondence in the late 1960's, that due > > >in some significant part to the emphasis put upon contrast by the > > >great Japanese manufacturers, principally Nikon and Canon, that > > >seemed to have persuaded a large number of photojournalists to favor > > >highest possible contrast (keep in mind that most of these folks did > > >then and still do tend to shoot wide open most often, eh Tina & > > >Ted?), Leitz designed the 1969 50 Summicron #11817, for max > > >performance at f/2. And wide open, looking at the MTF charts, no > > >question the contrast of 11817, especially at the lower spatial > > >frequencies > > >- 5, 10 & 20 line pairs/mm is significantly better than the DR. At > > >f/2,8 it is better than the DR but only on axis; at the near and far > > >edges the DR's contrast is superior and at f/4 and 5,6 it is > > >markedly superior, again except directly on axis. As to the current > > >50 Summicron, contrast is somewhat superior at the first three stops > > >whilst the resolution of the DR at medium apertures is better than > > >both later Summicrons. > > > > > > > > > > > > >From Leica's own MTF charts it is clear that the myth of the > > > >DR/Rigid lens > > >being soft and low-contrast is just that - a myth. Use that lens at > > >f/5,6 & f/8 and even at f/4, and you have an extraordinary > > >image-maker. And using a rigid 50 on an M8 as I do is even better, > > >since it eliminates the outside quarter of the image circle wherein > > >lies the vast majority of the design's "softness". > > > > > > > > > > > >Just my 2c. > > > > > > > > > > > >Seth > > > > > > > > >_______________________________________________ > > >Leica Users Group. > > >See http://leica-users.org/mailman/listinfo/lug for more information > > > > Chris Saganich MS, CPH > > Senior Physicist, Office of Health Physics > > Weill Medical College of Cornell University > > New York Presbyterian Hospital > > chs2018 at med.cornell.edu > > http://intranet.med.cornell.edu/research/health_phys/ > > Ph. 212.746.6964 > > Fax. 212.746.4800 > > Office A-0049 > > > > _______________________________________________ > > Leica Users Group. > > See http://leica-users.org/mailman/listinfo/lug for more information > > >_______________________________________________ >Leica Users Group. >See http://leica-users.org/mailman/listinfo/lug for more information Chris Saganich MS, CPH Senior Physicist, Office of Health Physics Weill Medical College of Cornell University New York Presbyterian Hospital chs2018 at med.cornell.edu http://intranet.med.cornell.edu/research/health_phys/ Ph. 212.746.6964 Fax. 212.746.4800 Office A-0049