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

[q.g._de_bakker]

JDM<br>You keep dragging in your favourite, the Biotar.<br>Did you know that the original Biotar (i.e. not the lens Zeiss East branded Biotar, to avoid the Planar name) is not a derivative of the Double-Gauss Planar, but yet another elaboration of the triplet?<br>The performance of triplets starts to fall apart at wider apertures. A solution employed to keep spherical aberrations and coma in check was to add another element. Most of these faults originate in the rear element, and one solution is to split the thing in two, keeping the same total power, but reducing the curvature, and thus spherical aberration and coma. Examples are the Tachar, the f/2.5 Cooke, and the f/1.9 Cinor B.<br>But it doesn't have to be the rear that provides the solution; another direction was taken in the Hektor: split each element, and you get more curved surfaces you can use to control the performance of the lens. The fast Hektor-Rapid, which evolved out of the Hektor, went one step further and (as did the Tachar) added another separate lens element, in the front (where the Tachar had one added in the rear).<br>There are two more places where you can add an extra correction lens in the triplet, between first and second, and between second ans third element/group. The Xenar put the extra lens between the front positive lens and middel negative lens of the Tessar-type triplet. (The (original) Sonnar filled the air space in the Xenar between that extra lens and the middle negative lens with glass.)<br><br>And the (original) Biotar is an example of a Tessar-type triplet with the extra lens added between the triplet's middle negative lens and the rear achromatic doublet.<br>It is not a member of the Double-Gauss family.

[dan_fromm2]

<blockquote>

<p>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.</p>

</blockquote>

<p>QG, naturally I can't find the quotation when I need it but I believe that's what Rudolph said he did. I prefer to believe the inventor's explanation than after-the-fact one you and JDM prefer. That the two explanations describe the same lens is fine, but since they differ they can't both explain the process by which it was invented.</p>

[q.g._de_bakker]

Dan,<br>I too would tend to believe what an inventor himself said.<br>I would also be wary of an inventor not being aware of a very succesfull new thing that appeared in his particular field of work, claiming not to be influenced by it in what he then invented, which turned out to look uncanningly as if he did know of and was influenced by that thing after all.<br>The Cooke Triplet triggered a slew of new triplet and triple derivative designs, and it would be rather remarkable if the Tessar would not be one of them.<br>People are people and can't help but do what people do. Rudolph is not immune to that.

[dan_fromm2]

<p>QG, I'm sorry you don't buy Rudolph's story. Kingslake did, see the link I posted in what, IIRC, was my first post in this discussion.</p>

[q.g._de_bakker]

People had time back then, James. Mainly because they did not waste it on all those time wasters that turned our days into more 'modern' times... They still knew how to spend their time well.<br>A nice example from the lens design world of how the believe in technological progress falls flat is the Zeiss 38 mm Biogon. It was designed in the days that people used slide rules, pencils and lots of paper. It had to be redesigned some 40 years later, and brute computer force did not produce a better lens (in fact, it was a tiny bit less good) than the slide-rule original.<br>In short: just because something was done long ago doesn't mean people didn't know what they were doing back then and the thing did not get done properly.

[q.g._de_bakker]

Dan,<br>As far as i am concerned, the jury is still out, and will never return a verdict.<br>Rudolph describes the background/origin of his Tessar in the patent. You can believe what he said, or point out that he would have had to claim it was an original invention else he and his employer would not have been awarded a lucrative patent.

[JDMvW]

<p>@QG<br /> Well, I will only respond to</p>

<blockquote>

<p>Did you know that the original Biotar (i.e. not the lens Zeiss East branded Biotar, to avoid the Planar name) is not a derivative of the Double-Gauss Planar, but yet another elaboration of the triplet?</p>

</blockquote>

<p>We've argued this one out too many times, and I didn't 'drag in' the Biotar, it was in the link given elsewhere, anyway.<br /> The Biotar that came out on the Contax S, from "Zeiss East" was the same lens as they had provided for the Exakta and <a href="/classic-cameras-forum/00b9KG">Praktiflex</a> BEFORE WWII, so it is hardly accurate to suggest that they so 'branded' it so to "avoid the Planar name".<br /> At the time the Biotar was produced for the Contax S, was Zeiss Oberkochen making <em>any</em> Planars, at least for 35mm format?.<br /> I thought in our old controversy you were the one arguing for the Biotar being "derivative" and I was the one arguing for its relative independence?<br /> Hmm.</p>

[q.g._de_bakker]

JDM,<br>O.k., o.k.! ;-)<br>Was interesting to note that the Biotar first appeared as a triplet derivative, was it not?

[JDMvW]

<p>QG<br /> O.k., o.k.! ;-)<br /> Yes, but the later Biotar (1939 and 1948) I'm concerned with most directly from my interests in crummy old East German cameras certainly is a double Gauss, wouldn't you say?</p>

<p>Actually, in what we call the Culture Historical paradigm in archaeology (Americanist archaeology from the 1920s to the 1960s), one of the primary tasks of the archaeological technician was to precisely identify what we've called 'families' here in the development of what was called "material culture". I am not part of that paradigm anymore, but I was trained in it, and tend to see the physical similarities as hints to derivation (as you argue for the Tessar connections above). Of course, in most archaeology, we are very fortunate not to have either historical records, or most particularly patent applications in which people put forward their case for their own interpretation. ;)</p>

<p>In Highland Burma (<a href="http://en.wikipedia.org/wiki/Edmund_Leach">link to author</a>), to summarize it grossly, every time somebody important in the system dies, there are funeral orations in which each relative tries to assert their own claims to kin closeness. In the end, some win and some lose.</p>

<p>Are our histories always so different from this? :)</p>

[rick_drawbridge]

<p>Amazing! We've gone from an educational dissertation on lens design, evolved through an anticipated slightly heated discussion on the finer points, brought Browning shotguns into the picture, and have sidled in the " Culture Historical paradigm in archaeology". It's this kind of stuff that brings me back to this Forum; keep it up, fellas!</p>

[q.g._de_bakker]

JDM,<br>Yes, the later Biotar is a Double-Gauss lens.<br>A thing that is making things a bit harder is that names were given to things, and reused for other things, not necessarily related, later. The Biotar is an example. The Aviogon derived Biogon another.<br>Other things evolved into something that is easily recognized, though the first examples that were given the name don't look much like what we know as such (Sonnar, for instance). Then there are those possibly converging lines of evolution, the Tessar could be an example of that.<br>From the moment that computers were put to use to calculate lenses, design families have disappeared. First a bit. Nowadays as good as completely. New lenses are given tasks such as having a small, light weight group that can be used to focus, or not being too expensive to make, with the computer solving the task of figuring out how to build a lens capable of good performance around such non-optical demands.<br><br>In highland Burma, people may lay claim to kinship to achieve political status. I don't know how that would transferto/be recognizable in the history of lens design, apart from having to claim that some solution is unique to be awarded a patent.<br>But be that as it may, the interesting bits are those about the different directions designers took when trying to solve the same problems, resulting in sometimes very similar, sometimes quite distinct lens families.

[chuck_foreman1]

I think we should start a new thread and pound out the Xenar, the Elmar and the Tessar. Themes and variations etc !!

Heres a link and it is more Zeiss centric. Not a lot of new information but an interesting link none the same!!"

 

http://www.panix.com/~zone/photo/czlens.htm

 

Lots of different lenses discussed!!

[Dan Deary]

<p>Not only did I get a long and entertaining discussion on the history of lens design but I but I learned a new emoticon from JDM which was ;-). He was winking throughout the whole discussion. I had to look it up.</p>

[JDMvW]

<p>Well, I was winking at least partly because the emoticon for irony, ".~" is so rare and usually unrecognized. :)</p>

[Two23]

<p>The Kingslake book is one of the standard references, and is well documented. It's good to read other source too of coursse, but I would certainly include Kingslake in any discussion.</p>

<p>Kent in SD</p>

[JDMvW]

<p>new thread?: "Xenar, the Elmar and the Tessar. Themes and variations"</p>

<p>Go to it, I'll watch as my stings heal. :|</p>

 

<blockquote>

<p>"There was this funny papery looking globe in the tree, so I poked with my stick to see what it was."</p>

</blockquote>

[MTC Photography]

<p>Rudolf Kingslake was a London borned optical designer, he got a MS degree from Imperial College of Science and Technology, under Alexander Eugen Conrady,latter maried Conrady's daugther, and edited Conrady's manuscript, published a two volume book on optical design.<br>

Kingslake was invited to USA to teach at Rochester University, in 1937 he became the head of the opticial design department of Eastman Kodak.<br>

Kingslake clearly has a british background, yet his opinions on lens design is not biased<br>

The section on Carl Zeiss Tessar is listed under Chapter 6 under the title "The First Anastigmats", Section IV The Unar and Tessar. While the Cooke triplet is listed in Chapter 7<br>

"The Triplet Lens and its modifications"<br>

Clearly, from historic development perspective, Tessar lens follow the Anastimats Unar lens line and not the Cooke Triplet line.<br>

The sequence of historical development is as follow:<br>

1)In 1890-1893 Paul Rudolph of Zeiss invented several variants of 4 element 2 group Zeiss<br>

Anastigmats, with front and rear cement doublets.<br>

2)In 1899, Paul Rudolph separated the cemented doublets in his Zeiss Anastigmats with air spaces into 4 element 4 group lens, the Unar. The Unar was a good design, but Ruldolph restored the cemented doublet of his Anastigmats but retain the air space, in other words, he kept the air spaced two front element of Unar, but replaced the air space of Unar’s 2 rear elemnts into a cementd<br>

Doublet, and Carl Zeiss Tessar of 1902 was born, it was a f/6.3 Tessar<br>

<img src="http://d6d2h4gfvy8t8.cloudfront.net/17083214-md.jpg" alt="" width="680" height="479" /><br>

<img src="http://d6d2h4gfvy8t8.cloudfront.net/17083215-md.jpg" alt="" width="680" height="510" /><br>

<img src="http://d6d2h4gfvy8t8.cloudfront.net/17083216-md.jpg" alt="" width="680" height="510" /></p>

<p>For derivatives of Cooke Triplets, Kingslake listed Heliar by Hartings in 1902, Ernostars, and Zeiss Sonnar, Leitz Hektor, Thambar, Leitz Elmar, Elmarit<br>

In other words: Carl Zeiss Tessar iss decendent of Zeiss Anastigmat-Unar<br>

Leitz Elmar is a descendent of Cooke Triplet</p>

[MTC Photography]

<p>In simpler terms, Paul Rudolph created the wonderful Carl Zeiss tessar by combining the front<br>

elements of his Zeiss Unar lens with the real doublet of his Zeiss Anastigmat. </p>

[MTC Photography]

<p>From geometric configuration, the Tessar has very narrow 1st airspace</p>

<p>For instance, 1907 Paul Rudolph Tessar 50mm lens has first element thickess 3.100, first air space 1.700<br>

While Cooke triplet has rather thick 1st airspace (triplet us pat. 2731884)<br>

first glass element 6.2500<br>

first air space 11.790<br>

Tessar lens always has its aperture stop placed at the 2nd airspace, the 1st airspace is too narrow for aperture stop<br>

On the other hand, Leitz Elmar has quite thick airspace, able to accomodate aperture stop<br>

at first airspace.</p>

<p>Reference: Warren Smith: Modern Lens Design</p>

 

[Rob_the_waste]

<p>JDM, the next time you and Q.G. get started in one of these threads, I'm gonna throw the both of you into the same room and sell tickets. Now, I'm gonna be late for work.<br /> ;-)</p>

[jim_baker6]

<p>While it is possible for the Tessar to have been developed from the Triplet, as Martin says this was not the way the design evolved and that evolution was sufficiently inventive for a Tessar Patent to have been granted. Zeiss and others produced many new lens designs but where Zeiss was unique was in the development of novel types of glass e.g. the barium crowns (in collaboration with Schott). This enabled Zeiss and others to develop the new lens designs. The front achromat of the Zeiss Anastigmat was 'old' glass and the rear achromat was 'new' glass. Ultimately the Tessar was formed by splitting the front achromat of this Anastigmat (what a mouthfull!). This provided two additional two glass-air interfaces for the designer to play with which, it appears, made a big difference. </p>

[JDMvW]

<blockquote>

<p>evolution was sufficiently inventive for a Tessar Patent to have been granted</p>

</blockquote>

<p>But see QG above on the issues of how patent claims are made. </p>

<p>There was once a patent on the 'idea' of the early automobile too (<a href="http://en.wikipedia.org/wiki/Automobile">Wiki</a> on Selden patents & Henry Ford), for example. </p>

<p>The simple physical similarity is still (even with written records) a better guide to historical connections than claims made by inventors about where they "got the idea".</p>

<p> </p>

[jim_baker6]

<p>Hmmm, yes, agreed JDM. It's inconcievable that Rudolph did not know about the triplet and who knows what actually went on inside his 'little grey cells'? But of course he worked for a company (Zeiss) that (like all companies) would present the narrative to suit its purposes (Patents, marketing, lens sales, etc.). It would suit Zeiss for the whole development to be a Zeiss development. But what Zeiss unquestionably did (with Schott) was develop the new glasses that were needed in the Tessar design. </p>

[dan_fromm2]

<blockquote>

<p>The simple physical similarity is still (even with written records) a better guide to historical connections than claims made by inventors about where they "got the idea".</p>

</blockquote>

<p>Why should I believe <em>that</em>?</p>

<p>"I'm a liar so everyone lies," I'm an PhD archaeologist and that's what we believe" and appeals to greedy capitalists are not arguments and won't convince. Documentation that will allow us to estimate the probablility that what actually happened and what was reported are strongly discordant will convince. Show us your data and calculations.</p>

[JDMvW]

<p>Because people, at their best, make their own case.</p>

<blockquote>

<p>"I'm a liar so everyone lies," I'm an PhD archaeologist and that's what we believe" and appeals to greedy capitalists are not arguments and won't convince.</p>

</blockquote>

<p>That's offensive, Dan.</p>