Archived posting to the Leica Users Group, 2010/09/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Really!? Hmmm, somewhere I read that only the very early Summicrons were rare-earth element lenses. Interesting since I've never seen a Rigid or DR with the yellow tint that is common to the rare-earth lenses. Phil Forrest On Fri, 24 Sep 2010 11:41:49 -0400 Chris Saganich <chs2018 at med.cornell.edu> wrote: > 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 > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information