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Triplets, Tessars, Sonnars, Optical Innovation, and the Nikkor-P


JDMvW

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<p><strong>Triplets, Tessars, Sonnars, and Optical Innovation</strong><br /><br /><strong>Preface</strong><br>

This is going to be very basic for some of you. It's also derivative. I wasn't sure whether to post it or not and where, but it's kind of long to tack on to another forum; and, since I had to plow (plough) through it to try to get it clearer in my own mind, I sort of hope that it may be useful to somebody else as well to have it drawn together from the various sources. <br /><br /><br />I have long since struggled through <em>Photographic Optics</em>, 13th ed. 1966 by Arthur Cox, M.A., B.Sc.F.Inst.P. London & New York: Focal Press. Some sections more than once, and I have carefully annotated some of the discussion and figures (in light pencil, I'm not a vandal, just a Goth from Gotland). <br /><br />I will recommend the book to you with some reservations. The history of photography and optics is no more clear of local prejudice than is any other branch of history. Cox, as his titles show, is definitely a Briton. So naturally enough, Cox tends to see the history of optics in fairly British terms. This is not so much wrong as it is a little provincial, but the Germans, Americans, French and citizens from other places with 19th and early 20th c. optics industries are just as provincial in their own ways.<br /><br />One of example of this, just in passing, is that Kodak (an important innovator, to be sure) features rather more prominently on Wikipedia's discussions of optics than it does in Cox or more easterly sources.<br /><br />Anyhow, some recent discussion on this forum led me back to Cox and some other sources to see what was what, since (unfortunately) reading something is not at all the same as "grasping" it. <br /><br />I am fairly dependent on Cox here, having looked on line for newer optical histories, only to find out that the European ones, at least, are a LOT more expensive than the old cameras I putter around with, and even as much as a lot of the lenses I am also accumulating and using. So Cox is what I have to work with, plus what look to be pretty good sources on Wikipedia (I am always amazed at how well Wikipedia does with non-political/non-controversial subjects).<br /><br /><br /><br /><strong>Why am I telling you this?</strong><br /><br />Well, on a recent comparison of a Carl Zeiss Jena (Olympia) Sonnar 180mm f/2.8 lens with a Nikkor-P 180mm f/2.8 lens ( http://www.photo.net/classic-cameras-forum/00bTe1 ) I said:<br /><br />"These are clearly in the same family"<br /><br />To which Q. G. de Bakker and Rick Drawbridge expressed skepticism about this "family". Q.G. also suggested that the Nikkor was more like a "Tele-Tessar."<br /><br />I'm here to say, that I was right (as I tend to think ;) ), but in the manner said in <em>Star Wars</em>, "So in a way, I was right when I said he had killed your father …"</p>

<p>I was sort of right about a 'family resemblance', but what I was seeing, given a generous dispensation, was not a <em>Sonnar</em> family resemblance but rather a similarity of what our good source, Mr. Cox, calls "Triplet Derivatives".<br /><br /><br /><br />So, what I am proposing to do here is to follow up to see what this all means. <br /><br /><strong>Cooke Triplet</strong><br />Cox says<br>

"When H. D. Taylor developed the Cooke triplet lens (named after the optical manufacturing company Cooke and Sons in York, England) a step was taken which was of<br />the greatest importance, as far as the design and production of photographic lenses was concerned. An early form of the lens is shown in Fig. 88a. It represented a complete break from existing tradition, as constituted at that date by Petzval lenses and by early symmetrical anastigmats." p248<br /><br />Wikipedia: http://en.wikipedia.org/wiki/Cooke_triplet <br /><br /></p><div>00bTyK-527479684.jpg.7285925599faa5f682db6932a82e956a.jpg</div>

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<p><strong>Tessar</strong><br /><br />The next step in development of this triplet form?<br /><br />"The most important single development, along these lines, is the replacement of the single rear element by a cemented doublet in the Tessar form of lens, shown in Fig. 89a. The refractive index of the negative element in this rear doublet must be less than the refractive index of the positive element in the doublet." p252<br /><br />Wikipedia: http://en.wikipedia.org/wiki/Tessar<br /><br />Here is what Cox is talking about<br /><br /></p><div>00bTyN-527479884.jpg.f0b730b260b7622884624cbff96bb985.jpg</div>
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<p><strong>Sonnar</strong><br /><br />After some discussion of lenses like the Ektar and Pentac, Cox comes to the Sonnar.<br /> [Wikipedia: ( http://en.wikipedia.org/wiki/Sonnar )]<br /><br />"The culmination of this line of development is found in the Zeiss Sonnar and Biogon constructions. The Sonnar lens, two versions of which are shown ln Figs. 90d, e, may be regarded as being derived from the lens of Fig. 90a by absorbing the central negative lens into the second member, or partially into the second member and into the third member. With this design an important feature is the thick second member. This serves the same general purpose as the thick negative members in the Speed Panchro, namely to reduce the Petzval sum. "<br /><br />Here is the figure that Cox refers to [slightly modified to label the parts directly]</p><div>00bTyQ-527481584.jpg.802470925cbd32e39fe5fcf697cac25f.jpg</div>
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<p><br /><strong>Summary</strong><br /><br />No conclusion is warranted, but I hope that this makes the salient characteristics more clear.<br /><br />The "critical attribute", as we say in archaeological taxonomy, for a Tessar is "the replacement of the single rear element by a cemented doublet "<br />For a Sonnar, "the thick second member".<br /><br />Since Zeiss named it a Sonnar, the Olympia Sonnar is clearly a Sonnar.<br />The Nikkor-P, is a Nikkor-P; but, yeah, it does look like a lot of the large number of variations of the Tessar design.<br /><br />On the other hand, ta-da, both Tessars and Sonnars (and many others) can all be seen as "Triplet Derivatives" as Cox calls them. :)<br /><br />Now will somebody here who actually knows something about lenses, please explain to me in simple words how to determine the lens formula or at least component number from the darned reflections?<br /><br /></p>
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<p>Actually the Sonnar (with its signature cemented triplets) was a development of the Ernostar (itself derived from the triplet.) The 180mm Nikkor P went the opposite way, going back to an Ernostar design, as did Zeiss with their SLR Sonnars, all of which dispensed with the cemented triplets, no longer necessary with the advent of multi-coating and high reflective index glass.</p>
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<p>A long time ago, in a galaxy far, far away...That's a pretty lucid presentation of some optical mysteries, <strong>JDM</strong>. I hadn't intended to imply that I thought your comparison was in any way wrong, merely not quite as close as you opined, but this post of yours very capably demonstrates the fluid nature of optical terminology and classification. I wish I knew and understood more, but on some other forums it can sometimes get fiendishly close to hair-splitting and navel-gazing. Thanks for a scholarly post.</p>
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What this demonstrates is that when you go back long enough in time, to when the present day variety had yet to begin evolving, you'll find that 'all things' were pretty much 'one thing', from which that present day variety has evolved. If you ignore the separate ways things have taken to become the different things they are today, everything is 'family' of everything.<br>Sonnar, Tessar, Biogon, Ernostar, and many, many more that have not been mentioned: they are all just Cooke triplets that have been messed with.
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<p>Thanks for posting such detailed info JDM. I've been curious about these triplets, as I'm thinking of selling my "better" lenses and using triplets exclusively. They do everything I want, and more. If I was shooting landscapes I would go with something that's sharper in the corners, maybe, but the triplets I have are really sharp in the center (where my subject usually is), have nice bokeh, and have a look that I like. My next experiment will be to replace my beloved Leica R 90 2.8 lens (seems to be a lot of elements in there) w/ a M42 mount 135 f4. Shots I've seen from those look very good, and I could buy three of them for the price of the Leica lens. 135mm is a little long for portraits, but I can't find an 85 or 90 Triotar.</p>
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<p>Fred, the symmetrical lenses are, according to Cox, and I think quite logically, as close to another 'family' as you can get. The modern Biotars and kin are among my very favorite lenses.</p>

<p>QG, you noted, of course, that I was actually saying pretty much that you were right, "in a way". ;)</p>

<p>In a day where photon squeezing is not so necessary as it once was, the Tessars and kin are definitely "back", not that they ever went away.</p>

<p>Thanks for your comments, all.</p>

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<p>All of the above and more. Many used to say the Tessar was a derivative of the Cooke triplet. Now we see where this line of thinking comes from. Many others have opposed this line of thought ..saying the Tessar was the breakthrough/out lens and a clear departure from the Triplet. So it's nice to see the marrying up of the derivatives to the Triplet. The Triplet being as you said a break from the Petzval and the symmetry of the previous designs. Everything that's new and different is really old ...again!! </p>

<p> </p>

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<p>Um, JDM, the story that Rudolph developed the Tessar by modifying a Cooke Triplet circulates widely but some sources, including Zeiss, deny it strongly. See Kingslake (http://books.google.com/books?id=OJrJrEJ-r9QC&q=tessar#v=snippet&q=tessar&f=false , p. 86) on this.</p>

<p>Its better, on the whole, to believe the man who did the work than people who made up stories long after the work was done.</p>

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<p>Very interesting JDM. Actually the Cooke Optical Company still exists in Leicester, UK, making lenses for the film industry, and was recently awarded an Oscar. I don't know if they make triplets anymore but their lenses are valued for the "Cooke look" apparently.<br>

http://www.cookeoptics.com/cooke.nsf/about/about.html<br>

It's descent was traced via the famous Taylor Taylor and Hobson lens company, later Rank Taylor Hobson, also in Leicester, but I don't know the full story.</p>

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<blockquote>

<p>Its better, on the whole, to believe the man who did the work than people who made up stories long after the work was done.</p>

</blockquote>

<p>Maybe,<br /> but as I said somewhere else, a successful design has many inventors.<br>

Nor, as I already said, are the German sources necessarily less 'provincial,' given all the nationalisms that are intertwined with this topic. I confess a leaning toward Jena, myself, but look at the lens diagrams for the "Cooke Triplet" and the Tessar, eh?</p>

<p>"Small step for man, giant leap for mankind."</p>

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<p>JDM, Paul Rudolph invented the Protar, the Unar, and the Tessar. In that order. These successful designs have one inventor. The Tessar has a Unar front group and a modified Protar rear group. What they look like has no bearing on how Rudolph came up with the design.</p>

<p>H. D. Taylor of Cooke, later Cooke, Troughton, Sims, invented the Cooke triplet. One inventor.</p>

<p>All of the design types mentioned were original, i.e., not derived from earlier designs. It is not always the case that a successful design has one inventor.</p>

<p>John, today's Cooke Optics derives from the lens-making part of Taylor, Taylor and Hobson. I believe that TTH's former metrology division still trades as TTH. TTH licensed H. D. Tayor's design from Cooke, sold triplets as Cooke triplets. As time passed Cooke became a TTH trade name and lenses of many design types were badged Cook. Cooke Optics current line of cine lense have nothing in common with the Cooke triplet but the word Cooke.</p>

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<p>Look, as said, I like the Jena story better myself, but it simply isn't black and white, either.<br>

It's good to see that Zeiss chauvinism is not dead, however.<br>

I feel good about that, especially given that the preface to my discussion above was precisely a disclaimer that Cox was a little, well, British.</p>

<p>However, are you seriously proposing that people in one place had no idea what was going on in other places at the same time? </p>

<p>I never said <em>anything</em> about the Sonnar being "symmetrical" - indeed the whole point of this post was to trace the non-Planar/Biotar/etc. designs.</p>

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<p>And I never mentioned anything symmetrical in this thread. I wonder where this came from?</p>

<blockquote>

<p>Fred, the symmetrical lenses are, according to Cox, and I think quite logically, as close to another 'family' as you can get. The modern Biotars and kin are among my very favorite lenses.</p>

</blockquote>

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<i>"QG, you noted, of course, that I was actually saying pretty much that you were right, "in a way". ;)"</i><br><br>I think i forgot to indicate that by adding a ;-)<br><br>It's a tricky thing, talking about lens families based upon what they started out as, since the important bit is why they were made different, and how. <br><br>I agree with Dan that lenses that embody the same idea do not necessarily have a common ancestor as such. They do have a common idea in their ancestry though. Triplets are based on a peculiarity in the Petzval theorem first noticed and employed by Taylor.<br>And i would disagree with the assertion that the Tessar is not an elaboration of that idea. It's not an Unar with a modified Protar rear group. It's a Cooke with an achromat as rear group. Just like the Heliostigmat is a Cooke with an achromat as front group, the Heliar is a Cooke with an achromatic doublet both in the front and the rear, and the Hektor is a Cooke with achromatic doublets in all three positions.
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