Which Nikon lenses are Planar design?

Discussion in 'Nikon' started by thomas_k., May 11, 2010.

  1. An article on wikipedia on Planar design lenses (symmetrical, six element air spaced) says: "A classic Planar design is the 105mm f/2.5 Nikkor produced from 1971 to 2006." Are there any other nikkor lenses with Planar design glass?
     
  2. Planar perhaps is not Nikon original design.
    I do not think there is a Nikon lens marked as Planar.
    For the sake of simplicity or similarity, some designs were close or identical to other original lenses.

    The best lenses like Planar, Sonnar, Tessar, etc. were suscessfully reverse engineered by others, sometimes even exceeding final product copy quality beyond the original lens.
     
  3. Planar is a Zeiss trademarked lens name. Their are a few other Nikkors that could be close to the Zeiss Planar design, I think the older Nikkor H 50mm is pretty close. But, that above quote is incorrect, like kind of way off, the 105mm is a Xenotar type, 5 element with one cemented pair, so totally NOT a "symmetrical, six element air spaced" . Read more at http://imaging.nikon.com/products/imaging/technology/nikkor/n05_e.htm
     
  4. google " mir and nikon ", the mir site has a huge amount of info on Nikon cameras and lenses. You might have to look at a lot of pages, but the diagrams of the optical construction will tell you.
     
  5. Christiaan
    There are two types of 105 f/2.5's one is a Sonar and the other is a Gauss type. Thomas I am not sure where they got the Planar from
     
  6. Yeah, me neither. Nikon's own optical historian claims it as a Xenotar type rather than a Gauss, so I went with that. Maybe its from the Rollei angle, those guys are known to 'discuss' back and forth about the merits of the Rollei TLR Planar vs Xenotar. Wish I still had a copy of Kingslake's book handy, shows early Planar vs Xenotar differences.
     
  7. Planar is a Carl Zeiss trademark.

    Xenotar is a Schneider trademark.

    There are some Xenotar and Planars that are almost indentical in design;
    ie both double Gauss types;

    with slightly different design tweaks; glass types; spacings; elements; since they are by competitors.
     
  8. Yes, Kelly you are very right, but the OP mentioned that the 105 Nikkor is a Planar.
     
  9. Both Mustangs and Camaros are American sports cars.
    Mustang is a Ford trademark;
    Camaro is a GM/Chevy trademark
    Planar versus Xenotar is like Mustang versus Camaro.
    Tessar is a Carl Zeiss trademark; Xenar is a Schneider trademark.
     
  10. "... I am not sure where they got the Planar from... "
    For sure Wikipedia is a very useful tool, but plenty full of inexactitudes. I`ve found many of them. Unless from a well known source of yours, as a general rule I`d always take internet with a grain of salt. Even Wikipedia.
     
  11. The Nikon 50 mm lenses are essentially Planar-types, i.e. double Gauss.
     
  12. Christiaan; Planar is a trade name; Gauss is the design to us optical folks. To the laymans world; one calls a Ford Mustang a sports car; one does not call a Ford Mustang a Camaro.
    Wikipedia is a mess of facts and gumbled stuff; sometimes inputs are from goobers; dolts; the lay public.
    Here I quote an actual physical published reference; where the new 1971 105mm was called a modified Gauss. Maybe the Wikipeda auathor cannot read; or works for Ziess and thus wants to plug a Zeiss trademark; maybe the Wikipedi author too has an agenda; or is lay and stupid too.
    The Review of the 105mm F2.5 Nikkor #418477 is in October 1971 Modern Photography. It reviews the newer optical design of the 105mm. In *THIS ARTICLE* it is where it says:
    *"have adopted a modified Gauss formula".*
    In the Nikon Schools in teh early 1970's they called the new 105mm a Gauss type lens. Typically vendors prefer to call their products by the design; and NOT anothers trademark of a competitor; ie Planar or Xenotar.
    It is not in the DNA of many Wikipedia authors to quote actual references; in some cases Wikepedia is more like a slanted advertisement; and thus trademarks are mentioned.
    In early Wikipedia articles they had the classical; lay, newbie dogma that all Kodak Ektars are a Tessar type design which is false; thus one has dolts writing encylopedias. There are 3, 4, 5 and 6 element Ektars. Wikipedia is free and has improved alot; often it has glaring mistakes; major holes; or a political slant from hell. Wikipedia requires actual folks to fix and remove the vast falsehoods to improve it. It is great but not always a real reference with references; more like a comic book; sales or BS one too.
     
  13. It's more complicated then I hoped for...
    Anyway, what then "Planar" means when stamped by Zeiss on their lenses? Apparently this article I read on wikipedia is all wrong even in giving definition: "six element, air spaced" - current ZF 85mm 1.4 Planar lens in nikon mount has 6 elements in 5 groups, 2 elements are cemented together. All this comes from questions I asked myself: Are Zeiss lenses unique in design or unique in craftsmaship? Are they (current ones available in nikon mount) so good because of their optical design or they are simply very well made?
     
  14. "Planar" is a trade name at Zeiss; like "Camaro" is at General Motors.
    An as analogy is that there are many types of Camaro models at GM ; and many types of Planar models at Carl Zeiss Optics.
    Zeiss *OWNS* the Planar name; like GM owns the Camaro name.
    Both the family of Planars at Zeiss and family of Camaros have a certain style; ie design.
    The Zeiss Planar family goes back to 1896; the GM Camaro to 1966.
    Lay folks might think that there is only one Zeiss Planar or only one GM Camaro model; but after some research learn there are many types.
    Another analogy is a circular saw; some folks call them Skill saws; one brand name. If Milwaukee makes a circular saw they will call it a circular saw; NOT a Skill saw; because one is using a Competitors brand name.
    There are many makes of Double Gauss type lens designs; ie Carl Zeiss *Planar* ; the Schneider *Xenotar*; a few Eastman Kodak *Ektars* ( The Ektar Kodak brand name just means a quality product IT DOES NOT MEAN A DESIGN TYPE AT ALL) . One can have 6 elements all air spaced or 6 with a couple cemented together and still have a double gauss lens type.
    If folks here seek a simple answer; ask yourself what only shoe does a woman use; or engine a Camaro has.
    One has 7 element Carl Zeiss Planars; 4 cylinder Iron duke Pontiacs engines in Camaros.
    Lay folks might say the only engine in a Camaro is a V8; or a Zeiss Planar is only one exact design; and not fathom 100 + years of Planars; or 40 years worth of Camaros
     
  15. It is more common to say a lens is a (Zeiss) Tessar type design than probably saying one is a (Zeiss) Planar type design.
    When the GM Camaro came out sold folks called it GM's Pony car; implying copy or like the Ford Mustang.
    If one said the 1967 GM Camaro was a copy of the 1964 Ford Mustang; it sort of was; but not really.
    Just implying hits the hornets nest.
    There are many Carl Zeiss Planar variants over 100 + years; some calling it on exact formula is a bit simplistic
     
  16. Kelly - your sport car analogies are not very clear to me - I drive a minivan...
     
  17. How about minivan and SUV are NOT brand names;
    but Honda has its *ODYSSEY*;
    Toyota has its *SIENNA*;
    Kia has a *SEDONA*;
    Mazda has the *MAZDA5*
    If lay folks started to substitute *ODYSSEY* every time they really meant SUV or minivan others might get confused too.
    Again in since it still does not sink in; *PLANAR* is a Carl Zeiss Tradename; like *SIENNA* is a Toyota tradename
     
  18. Another analogy is to say a Nikon F is an SLR; not to say a Nikon F is an Exakta VX design
     
  19. The assumption here that lead you astray is your narrow " Planar design lenses (symmetrical, six element air spaced)"
    It is like assuming all minivans have V6's and are made by one vendor Acme
     
  20. So, Zeiss calls ALL of their 50mm and 85mm lenses Planars regardless of their optical composition or characteristics?
     
  21. So, Zeiss calls ALL of their 50mm and 85mm lenses Planars regardless of their optical composition or characteristics?​
    No, they have made Sonnars too in those focal lengths. Planar is a lens design, but the name "planar" is trademarked by Zeiss. So the same basic design is used by other companies, but it's not marketed as "planar".
     
  22. Thomas;
    Zeiss made the 50mm F2.8 Zeiss Tessar; a different optical design. ( 4 ELEMENTS 3 GROUPS)
    Zeiss made 85mm Tessars; the tele tessar
    Zeiss made the Zeiss Sonnar 85mm F2
    ***Zeiss does not call all their 50mm or 85mm lenses Planar; nor does GM call all their cars a Camaro.
    A CARL ZEISS pair of eyeglasses with a single element +11 3/4 diopter is a 85mm lens; it is NOT a Zeiss Planar but just a super strong pair of eyeglasses.
    There is a good chance that a Zeiss lens in 2020 that is double Gauss type design will be called a *Zeiss Planar*
    and a good chance a GM/Chevy sports car in 2020 will be called a *Camaro*.
    Both Zeiss and GM own the trademarks Planar/Camaro; they probably not use them for dime store maginfying glasses or golf carts.
     
  23. ***Maybe the impass here is the word trademark is not understood.
    Zeiss owns the trademark name Planar when used for lenses.
    Some how this is not sinking in yet.
    A Zeiss Planar is a brand name for a double Gauss type of lens design.
    There is no rigid law that says a Zeiss planar HAS to be some exact rigid formula or that a Ford Mustang has to be some very specific design
    The 80mm F2.8 Xenotar here is a double Gauss lens design made by Schneider.
    They do NOT call it a Planar or a Ektar or Rokkor; or Acmegon because their competitor(s) own these names. Thus Schneider calls their double gauss design a Schneider Xenotar.
    Schneider owns the Xenotar tradename.
     
  24. Kelly,
    There is no impass here just learning process, your explanations are apreciated. Thanks! Which nikkors have a double Gauss formula? Oscar mentioned 50mm - all of them? any other focal lengths?
     
  25. Thomas
    the 45mm F2.8 Nikkor GN and new variant Nikkor -P are a 4 element 3 group; NON double Gauss design; ie a Tessar design.
    Tessar too is a Carl Zeiss trademark; but it is used more often to say a lens is a Tessar type design than Planar type.
    The "all or them" is a very dangerous assumption; since Nikon has made lenses since world war 1!
    There are also 50mm lenses for 16mm cine/movies with 4 elements; and even 60 year old 5cm enlarging lenses that are 3 elements
     
  26. the 50mm F2.8 Nikkor GN and new variant Nikkor -P are a 4 element 3 group; NON double Gauss design; ie a Tessar design.​
    You probably mean the 45mm GN nikkor ;-)
    I'll rephrase it to mean "all of the 35mm camera F mount 50 mm Nikkors and the 50/1.8 Series E". With that statement, I should be pretty much covered.
    I have a Carl Zeiss Tessar on my cellphone, very short focal length.
     
  27. I recommend you read a book about photographic lenses, such as "Photographic Lenses", by C.B. Neblette, New York: Morgan and Morgan, 1973, or similar. Check your public library.
    In 35mm, full-frame, Nikon interchangeable lens world, most all of the 50, 55, 85, and 105(except the old 104/4 Micro, and the historic 105/2.5) lenses have been double-Gauss designs.
    Double-gauss designs are good for normal or slightly narrow angles of view, fast aperture, plus fairly flat field. The vast majority of the 50mm through 100mm designs of all the manufacturers have been double-Gauss designs. Most 135mm and longer are not; most 35mm and shorter are not.
    Zeiss calls double-Gauss designs 'Planar'.
    Zeiss calls inverted-telephoto designs 'Distagon'.
    The original Zeiss name 'Tessar' from 1902 has passed into common use as a generic term for a 4 element lens of a certain modified triplet design.
    Zeiss names their lens models loosely according to the optical design; Leica names them according to their maximum aperture; Most of the other companies give[gave] all of their own products one name, eg: Zuiko=Olympus, Takumar=Pentax, etc. Hope this helps.
     
  28. Kelly, I really appreciate your explainations. I do have a well rounded optical knowledge, so you're preaching to the choir, so to speak. I was merely pointing out that in the Nikon article written by a Nikon optical engineer and Nikon Corp. optical historian he states that the 2nd optical formula for the 105mm 2.5 is a Xenotar type, which I find odd since he more clearly could have said 'Double Gauss' and saved us all a bit of brain power. I do find your car analogy quite amusing.
     
  29. If a maker such as Nikon; Canon, Minolta, Apple; Motorola used the word Tessar on a lens; one is going to see Zeiss pull out the gloves to defend its old trademark. A Judge could halt sales. Tessar probably is used by many of us as sort of a generic term; but probably is not legal. Zeiss still uses the Tessar brand name.
     
  30. I have the older 105 2.5 that is often said to be a sonnar and is often said to be the same design as the older LTM Nikkor but made for the F mount. Is that actually true or is it something else.
     
  31. Reminds me of how I refer to petroleum gelly as vaseline, even though the tube at my home is manufactured by Nivea, or how my American friends Xerox their notes, while I photocopy them, and how Starbucks promotes their own cup size names.
    Do you refer to a personal tape cassette player as a Walkman? If a photographer uses GIMP to process his/her images, are they gimped or photoshopped? In almost all cases brand names are more catchy than their scientific alternatives. If the intent is sufficiently communicated, how much does it matter that we use popular trademarked names or their scientific labels in general conversati0n? If you have a cold do you ask for the pharmacy brand acetaminophen or Tylenol?
    Giving him/her the benefit of doubt, the wikipedia contributor is guilty of ignorance or carelessness. The article should be flagged for inaccuracy. However I see no problems with lay folks talking about Planar or Tessar lenses, AS LONG AS they recognize that Zeiss owns these names, and the usage is not commercial or academic.
    Who knows, maybe in 50 years, Planar and Tessar will be added to Meriam-Webster dictionary.
     
  32. Kelly - your car analogies are a little misleading, as the Camaro and the Mustang are much more different than the Planar and Xenotar. Also the lenses are basically a platform for design, while the cars are specific models (with some variations of course, but all roughly the same skeletons). A better anology would be to describe the lenses as a Corolla and a Civic, as those cars have been copied many times, and the platforms have been used for many other models. I believe the Geo Prizm as actually an almost exact duplicate of the Corolla, minus some minor differences in powertrain and interior.
    Also like the Planar and Xenotar, people will endlessly argue about which is better, even though the base model Corolla and Civic are pretty much the same. Y'know, pre-tuning.
    As far as which Nikkors are of Planar design ... get a lens chart, and look at the specs. Remember though that Zeiss lenses are known for their craftsmanship. Just because a Nikon E series lens is Tessar or Planar design doesn't mean it's not a cheap lens - it just means that there are a X elements in Y order.
     
  33. I don't think any of Nikon's photography lens is 'planar'. But Zeiss makes a wide range of lenses for Nikon and the majority of these lenses are 'distagon' except 100mm makro, which is a planar lens. Please note that objective lenses (2X -40X) for Nikon fluorescent microscope are mostly planar lens.
     
  34. All you guys are forgetting one major lens type. The 'Coke bottle'. At least that was what we called a really bad lens back in the seventies. Poor resolution and contrast at any aperture, soft focus, but not on purpose. Talk about stealing a trade name. So.....has anybody here ever owned a 'Coke bottle'?
     
  35. Christiaan;
    RE :"Kelly, I really appreciate your explainations. I do have a well rounded optical knowledge, so you're preaching to the choir, so to speak. I was merely pointing out that in the Nikon article written by a Nikon optical engineer and Nikon Corp. optical historian he states that the 2nd optical formula for the 105mm 2.5 is a Xenotar type, which I find odd since he more clearly could have said 'Double Gauss' and saved us all a bit of brain power. I do find your car analogy quite amusing."
    " Yeah, me neither. Nikon's own optical historian claims it as a Xenotar type rather than a Gauss, so I went with that. "
    Many Zeiss Planars and Schneider Xenotars are very similar in design. If one wants to plug Zeiss one can call a Acme 80mm F2.8 a Planar design; if the plug kickback; or bias is towards Schneider; one can call the Acme 80mm F2.8 a Xenotar type design. One could call an AMC Pacer a Mustang type design; or a Camaro type design too.
    Since the average photographer has an 8th grade educational level as far as science; referencing brand names like Xenotar or Planar makes sense. They do not own Oslo; or have done raytracing; or own 3 Kinglake books; Smith, Conrady; have Schott glass books like some of us. Most photographers have never heard of Gauss; or a Gauss design.
    Neither Planar nor Gauss brand names have any exact ties to an a exact optical formula; or element cementing; thus lay folks are confused; they have this simpleton rigid model that fits one model lens; but it does not fit another. Thus one has 6 and 7 element Planar Zeiss lenses; 4, 6 and 8 cylinder Camaros.
    There are Xenotars and Planars that look like they are exact clones; and ones that look alot different; ie glaring; ie one extra element. Thus dwelling on whether an Acme 80mm F2.8 is a Planar or Xenotar is absurd from an Engineering standpoint; since neither Planar nor Xenotar has an exact definition.It is as absurd as dwelling on whether an Acme car is closer to a Pontiac or Buick; but one does not know that Buick and Ponitacs were made for many decades.
    Even if the Brand A and Brand B have the same optical diagram; the lay public still; does not know the optical glass types; lens curvatures; tolerances; lens mount tolerances; testing criteria.
    It really is not too odd to reference brand names suchs as Xenotar or Planar; it confuses folks less that do not own optical books. Usage without mentioning the owners name is poor practice in a publication; and usually is deeply frowned apon when it is a competitors legal brand name. Thus GM probably is not going to say a Camaro is a Mustang copy; but th so called Nikon expert called the 1971 105mm a Xenotar (a Schneider brand name).
    The old Modern Photography test articles called it a Guass design; and so did the Nikon School's too. The Nikon author may not have read the magizine or gone to a Nikon school in the 1970's.
    In writing for technical publications flaws like acting like brand names are generic is a major one; the editor has one correct ones goofs. It is like having 10 spelling errors
     
  36. The Planar brand name has been used on many differnet Gauss type Zeiss lenses. The trademark is over 100 years old. Simple minds here want it to be one rigid exact design; when there are even 6 and 7 element lenses. Since it is not some exact design; reference to it causes lay folks to be confused; Acmes lens might be like a Planar in a Rollei TLR; or like one in a Blad Slr. A main tenent of many photographers is to argue about brand A versus brand B of lenses. Thus folks ponder whether a Xenotar or Planar is better on a TLR but ignore the camera is bent; or a mixture of parts; or has its bright screen causing a focus bias.
    None of Nikons lenses are a Planar brand name; that is a Zeiss brand name. Maybe if this is mentioned a million times it will sink in. Some Nikon lenses are a Guass type design; like the Zeiss Planar is. Since the car analogy does not sink in either; Ford does not sell new Camaros; and GM does not sell new Mustangs.:). Saying a Camaro is a Mustang like design happened in Detroit when the 1967 Camaro came out; some folks called the Camaro GM's "pony car" so they did not use trademark Mustang.
    Diluting trademarks can cause confusion; folks throw "Planar" around like it is one exact formula; this causes other lay folks to get confused
    The 50mm F2 Xenon in a Retina is a Gauss type lens; so one could throw that name in to add to the confusion.
     
  37. Kelly,
    I think you have made your point - Planar, Tessar, Ektar and others are trade names. Repeating the same thing six times doesn't help. All lenses were invented by someone or some corporation, leaving their name on the design. Some are in public domain by this time.
    I am not an expert on lens design, nor the history of lenses. I find the subject intensely interesting and worthy of more study, but in the interest of civility, I may have something to contribute.
    Lenses have two elementary shapes, convex and concave. They can be combined into a doublet called an achromat. The positive lens forms the image, and the negative lens has less power but with a glass with greater dispersion power (separating colors). The negative lens therefore reduces chromatic aberation by forcing the colors dispersed by the positive lens back together again. This "simple" device was invented in the 18th century, the design stolen by the optician contracted to make the lenses, and subjected to litigation lasting nearly two centuries. (We get our litigious society honestly from our British forefathers.)
    Two achromats back to back form the basis of a Gaussian doublet, one of the basic lens types which evolved into the mostly symmetrical Planar and Summicron lenses. The other basic compound lens is a Cooke triplet (also invented by someone), consisting of two convex lenses with a negative lens in the middle, usually spaced. The most common variation of the Cooke triplet replaces one of the convex lenses with an achromatic doublet, seen in the Zeiss Tessar, Leitz Elmar and many other variations. Another basic design consists of two negative lenses with a strong positive lens in the center. I don't know the generic title, but the design is found in Hastings triplets and the Zeiss Distagon.
    Other elements are added to these basic designs (achromat, doublet and triplet) to correct for various optical problems - curvature of field, chromatic aberation and coma to name a few. With modern multi-coatings, internal reflections and light loss are largely moot, so lenses have become much more complex. Yet we can see their roots in the basic symmetry of design. (Lenses designed to work closely tend to be more symmetrical than those optimized for normal photographic distances.)
     
  38. Edward;
    The point about tradenames seems to *NOT* be sinking in to some here; since the constant reference is being made like "Planar" is a specfic design; and not a makers 100 years worth of designs. Sometimes the light bulb goes off in folks heads when facts are repeated; it gets through blockheads.:) . These trademarks have not gone generic; the lack of respect for trademarks here shows; which is strange because many photographers whine when others use their images; ie double standard. Acting like registered trademarks are generic and are in the public domain by lay users just dilutes what a brand name is worth.
    The Xenotar referenced in the the Nikon link by Christiaan is really the Schneider Xenotar that was designed by electronic computer in Switzerland; the 80mm F2.8 for the Rollei TLR. This was one of the first lens ever designed by computer; ie non human computer. This new lens article is in a early 1950's Photo magazine I have. It took only a couple years versus a decade of hand calcs; ie when a computer was a persons job title in optical design. This Schneider Xenotar 80mm F2.8 came out first; then the Zeiss Planar 80mm F2.8 as the 2nd source lens later. If one mentions that the 80mm F2.8 Zeiss Planar is the 2nd source lens on a Rollei TLR most folks go nuts; ie their brains cannot accept that the Schneider Xenotar was used first in that TLR; I think in the C model.
    It is really poor practice for a Nikon article to use anothers brand name like it is generic; Schneider could do this too and try to make Nikons tradenames generic.:) The article should at least mention that Xenotar is a Schneider name; ie gain some professionalism. In the old days with editors one could not publish stuff without real references; today it is common.
    http://imaging.nikon.com/products/imaging/technology/nikkor/n05_e.htm
    In lens design programs we Engineers use there are examples of old designs one can play with. Most of the time the patent number; name of the lens and guy who designed it are right there; plus reference that the name is a trademark. One can start with a classical design as a start and go in and ruin it is short order; or try to improve it!:)
    The Zeiss Planar ; ie double Guass was NOT used much before lens coatings; it really became a viable post WW2 when coatings became common. The design had too many air to glass interfaces; thus too much loss with a non coated lens. Thus the simpler Zeiss Tessar; the "eagle eye" lens was the pre ww2 king; in the uncoated lens era; since it has a higher contrast due to only 6 air to glass lossy interfaces; ie less.
    Much of the confusion here is due to folks assuming. There are Zeiss Planars and Schneider Xenotars in some formats and cameras that look like exact clones. Then there are others where a Zeiss Planar and Schneider Xenotar looks way different; ie different number of elements; some cemented; etc. Thus some Zeiss Planar and Schneider Xenotar are extremely close; others way different to a detail oriented person. The lay public gets confused. They want Black and White answers to a grey area issue. They want a 1 bit answer to a 8 or 16 bit issue. Really life and designs are not so well defined or rigid; there are many exceptions.
    Even the 100+ years of optical books are not well exact. If the book is by the late great Kodak Kingslake; there is a Kodak slant to the book. Thus the 1950 book of his here has many Kodak lenses. The Canon FD lens book here from Canon that is about 7/16" thick here has a Canon slant. My Nikon Nikkormat handbooks have a Nikon slant.
    There a repeated errors too in some books. In optical design one has the vexed subject of references; which way is positive.
    In Zeiss one has the complex breakup due to WW2 and reuniting again; and vast decades were some trademarks were used on the other side of the iron curtain. One had two different Ziesses; thus the same type lens made in the East might not have the Wests trademark before the breakup.
    The optical companies trademark lens names are also placed sometimes on low cost stuff like P&S cameras; and even some cellphones. Thus the name might be on an aspherical molded plastic lens or few or one element; and have nothing to do with that camera lens from 1960.
    Here it is amusing to read that folks think that these lens marketing lens brand names are one type; when there are so many variants; ie different designs. In a lay sense it is like if folks assumed where is one alloy of steel; one type of plastic; one type of brass; one type of shoe; one type of beer; one type of fishing lure. One could say there are light and dark beers; strong and weak beers. To a detail oriented person there are many variants; to an assumer type there is only a few types. There really has to be at first; but then each digging you find out that one has a fractal situation; there are a zoo of types. Thus to me a "Planar" is a zeiss sort of Gauss design; not one of super exactness; since there are many variants. There are Russian lenses for my Zorki that are a Gauss design.
    Even is somebody firmly boxes in the lens diagram; elements and groups one still does not know the refractive indexes. One can take a 40 year old design and throw in some more exotic glass; make a few surfaces non spherical and improve a design; and it looks the same in the lens catalog.
     
  39. In another, unnamed forum, there have been many threads devoted to which of the six or seven versions of the Summicron are the best (I have a dual-range Summicron of 1964 vintage). I expect to be flamed for suggesting it evolved from the whimsy of a 19th century mathematician, not created whole by God.
    Maybe it's time to Zip (tm) it up.
     
  40. Thanks to all, my esteemed gentle folk of this session of the photo.net senate. Points well made all around, in great detail. At this time the chairman will gavel this session to a close in order to minimize filibustering and overload of photo.net servers.
     

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