Zeiss Sonnar 50mm F/1.5 - Overview
Introduction
The Carl Zeiss Jena Sonnar 5cm F/1.5 (1.5/50) is a 50mm standard lens for range finder with a very bright F/1.5 aperture manufactured by Carl Zeiss Jena from 1932 until today. This lens has not only a long history but maybe the most interesting story of all photographic lenses. It was not only one of the very first full-frame (35mm) lenses it was the fastest one too. It was this lens that put Carl Zeiss Jena on the map as one of the most influential photographic and cinematographic lens manufacturers world wide. It was a huge success for CZJ but faded almost into irrelevance decades later. It was copied several times by other manufacturers and more than once started the rise of brand names that everyone knows today.
Because of this long and turbulent history a lot of different versions exist of the Sonnar 1.5/50 Today. CZJ changed the barrel design and internal lens design a lot of times. They introduced this lens for different camera mounts and systems. I could not find a complete overview over those versions. Technical specs were missing completely for all Sonnar 1.5/50 build before 1960. The situation becomes even more confusing with the Sonnar copies from Japan and Russia. Especially because of the Jupiter copies the Sonnar 1.5/50 has a bad reputation as an unpredictable fake gamble.
That is why I want to give an overview over the different versions of the CZJ Sonnar 1.5/50. I want to help people to know which lens versions exist, how to separate them and to share the story of Ludwig Jacob Bertele's Sonnar 5cm F/1.5.
TOC
Relevance
The Sonnar 5cm f/1.5 is a milestone in the history of photographic lenses. It was and is an outstanding lens that shaped and revolutionized the photographic world.
1932 when Ludwig Bertele calculated and created the Sonnar 5cm f/1.5 in Dresden. The world had not seen such a fast standard lens before. This lens was one of the first interchangeable lenses created for the then new 35mm film format (Kleinbild / full-frame). It was the fastest lens for this format at the time beating the competition by more then one stop difference. Although it is a tiny range finder lens it offers sharp and contrasty images wide open and opened a world of indoor photography for photographers of the time. It took over 2 decades and another groundbreaking Zeiss invention before the competition was able to outperform the Sonnar 5cm f/1.5 in speed and image quality.
Already 1922 Ludwig Bertele created a lens that is considered a milestone: the Ernostar 8,5cm f/1,8 for the Ermanox camera. He calculated this lens as employee for the Ernemann-Werke in Dresden. This 4.5x6cm (Mittelformat / medium format) camera and lens caused a photographic hype. The reason was that it allowed taking hand hold images indoors without flash light and tripod. New genres of photography where created because of the Ermanox and the Ernostar. Stage photography in theaters or court photography are such examples. The wide aperture of the Ernostar allowed for available light photography with 1/15s or 1/30s! Film emulsions of the time where quite slow with ISO16. Despite the great start the Ermanox camera was already discontinued in 1930 through the huge international success of the Leica I.
When Carl Zeiss Jena released the Sonnar 5cm F/1.5 for the Contax camera it generated great international interest. It was even faster then the Ernostar but at the same time very tiny and light. It's bright aperture combined with the new Agfa Isochrom promised unseen available light performance. While the Ernostar has its famous status it was the Sonnar 5cm f/1.5 that appealed to the masses. The simple reason is it allowed taking photos of everyday life. A Contax with a Sonnar 5cm f/1.5 was very expensive but not out of reach of normal people. If you could afford one it was the perfect tool for candid photos of your family or important events.The Sonnar 5cm f/1.5 was the one bright lens everybody wanted to use on their camera. Even Leica owners enviously looked at Zeiss and wished to use this one on their Leica camera. It was not until 1949 / 50 until competition was able to catch up with the release of the Leitz Xenon 5cm F/1.5, Nikon NIKKOR-S 5cm F/1.5 or Voigtländer Nokton 5cm F/1.5.
The Sonnar 5cm was designed for the Contax I rangefinder camera. The Contax RF version of the Sonnar is missing a focus helical and ring and only measures 41mm / 1.6. Although it is so small it has a wide maximum aperture of F/1.5. To achieve this Ludwig Bertele invented a completely new lens design: the Sonnar. It offered a solution to the problem of light loss through reflections especially within lenses with more than 3 glass lenses. It can't been overstated how important this design principle was at the time when it was patented. At the time of release of the first Carl Zeiss Jena Sonnar 5cm f/1.5 for the Contax I there where other full-frame patents offering a bright F/1.5 aperture like the Biotar or Schneider Xenon. In practice the light loss through reflections by the higher number of glass surfaces made them only usable in theory. This changed drastically after WWII with the broader availability of anti reflection coating. The coating technology provided another solution to the problem the Sonnar design solved and made other more complex lens designs practicable.
After WWII several developments came together that caused the Sonnar 5cm to become less and less important. One major development was that all lens manufacturers started to use anti reflection coatings. This new technology increased contrast and flare resistance of lenses and solved the issue of light loss through reflections. This alone made more complex optical designs with better correction practicable. Thanks to single and later multi coating it was finally possible to use and improve Xenon / Planar optical designs. Manufacturing of Sonnar lenses is very expensive and time consuming since they use a lot of kitted lenses and grinding those very spheric lenses is a difficult task. So the Sonnar 5cm f/1.5 never was a mass product. In comparison manufacturing of fast Planar lenses is easier, faster and way less expensive. Planar designs are easier to correct for optical defects too.
Another development was the rise of Japanese photo industry and their competition of the fastest lenses. At the end of the 50ies there where several new lenses that sport an aperture of F/1.1 or F/1.2 and had surpassed the Sonnar 5cm f/1.5 in speed. Some were Sonnar designs too but the NIKKOR-N.C 5cm f/1.1 and the 1961 Canon 50mm f/0.95 were Planar lenses. But to win the international mass market Nikon, Canon, Pentax and other Japanese manufacturers started to offer affordable 50mm F/1.4 Planar type lenses with their own cameras that soon became a standard in the photographic world.
The most impact came from the development of SLR cameras after WWII. In the 1950ies the single lens reflex camera technology advanced with big steps and by the end of the 50ies sales of SLR cameras outsold all range finder cameras. The effect was so dramatic that almost all manufacturers dropped their range finder offerings and switched to SLR camera production. The Sonnar 5cm can not be used on SLR cameras. By design it uses a very short flange distance (distance between the lens mount and film) it is not possible to mount it at a camera that uses a mirror between lens and film / sensor. The dominance of SLR cameras that use a mirror for focusing and metering caused that the Sonnar 5cm was relegated for 4 decades.
The effect of downgrade might even made worse through the Soviet Jupiter-3 production that started 1948 and run until 1988. Although the Jupiter-3 is a Sonnar 5cm F/1.5 clone that was produced with original Carl Zeiss Jena machines and tools the build quality seems rather spotty. Nevertheless most photographers praised the Jupiter as a sharp and contrasty lens. The issue with Jupiter lenses is the high amount of fake lenses especially for the M39 / LTM Sonnar 5cm F/1.5. It is rather easy to rehouse a Carl Zeiss Jena Contax Sonnar in a LTM Jupiter-3 body. The high demand for LTM Sonnars caused a flood of not authentic CZJ Sonnar lenses to a point where most people consider buying a 50mm Sonnar lens as a gamble. The truth is that there are only a small amount of fake lenses mostly LTM Sonnar 5cm. Most of them can easily be identified. Then there is a number of lenses that look like fake ones but are considered as transition lenses. They are build partly from original CZJ parts mostly in the years after WWII. Then there is a very small number of prototype lenses build by CZ Ikon and Jena. Although usable those prototype and transition lenses might be more of a collectors item since they tell a lot about the history of Zeiss Ikon, Carl Zeiss Jena and KZM.
In the year 2000 the Sonnar 5cm F/1.5 had no relevance at all anymore. There was no production of this lens and only in the shrinking niche of range finder users there was a small number of people collecting and using the CZJ or CZ Sonnar 5cm F/1.5 for their own pleasure. This changed somewhat in 2005 by Carl Zeiss entering the analog film range finder camera market with the Zeiss Ikon ZM after 45 years. One year later Carl Zeiss started selling the C Sonnar 50mm F/1.5 T* for ZM / Leica M mount. The C Sonnar was a completely new and updated design. It is based on the original 1951 Carl Zeiss Sonnar 50mm F/1.5 T but uses a new optical calculation that is a mix of Planar and Sonnar design. Manufacturing is done by Cosina in Japan. The lens offers a modern handling and better corrected image quality while staying close to the Sonnar signature.
Since the rerelease of the latest Carl Zeiss C Sonnar 50mm F/1.5 T* the camera market changed significant. Analog cameras where replaced by digital rangefinder and SLR cameras. A lot photographic films where discontinued because of the shrinking demand. Digital SLRs dominated the market for years. Digital mirrorless cameras slowly replace DSLRs. Mirrorless cameras allow to use vintage range finder and SLR lenses again. A lot of people started to use those old manual lenses on their modern mirrorless camera. The newly demand for old lenses caused a boom of vintage and new manual lenses. New manufacturers started to appear mainly from China. This boom slowly elevated the analog and range finder marked too. But it elevates the interest for Sonnar 50mm lenses too. MS-Optics, a small Japanese one-man company, started to churn out several ultra fast Sonnar design lenses, the MS-Mode 1.3/50, Sonnetar 1.3/50 and the famous Sonnetar 1.1/50. Even the Russian Jupiter-3 was rereleased by Lomography and KZM in 2016.
How relevant is the Sonnar 5cm f/1.5 today? After decades of slumber the Sonnar 1.5/50 is getting manufactured again. Zeiss still produces this lens even after 90 years (by Cosina in Japan). Ironically it is one of the very first 35mm film lenses Carl Zeiss Jena had released and it might become one of the very last Zeiss will produce. At this moment there are rumors out that Zeiss will leave the photographic lens market.
There is a small base of users with a high interest in this lens after all. Some favor the vintage look of images the Sonnar lens creates compared to the perfect look that Planar lenses create. Some are interested in the history of Zeiss and the Sonnar lenses. Others look for a small lens with good IQ. Even Today 90 years after Ludwig Bertele created it there are only very few 50mm lenses that are so small that provide the same or faster aperture with better image quality.
When we look for comparable sized and fast lenses there are only 5 already mentioned modern lenses competing with the Sonnar 5cm F/1.5 today. There are the MS-Optics MS-Mode 1.3/50, SONNETAR 1.3/50 Slim and SONNETAR 1.1/50. These are Sonnar designs too. They improve on speed but only marginally on IQ. Then there is the Carl Zeiss C Sonnar 1.5/50 that is a mix of Sonnar and Planar design. It still has the Sonnar signature IQ but improved sharpness. The Voigtländer Nokton 1.5/50 II is the only Planar design in this list and it offers maybe the best IQ of all of those lenses. Leica is missing here but all of the Summilux 1.4/50 are bigger than the Carl Zeiss C Sonnar.
Today the Sonnar 5cm f/1.5 is seen as more of a collectors item by the majority of people. There sure are collectors out there that buy Sonnar lenses purely for their rarity and heritage. Compared with some Leica offerings the Sonnar is a pretty budget friendly lens though. After all a lot of people still buy and use the Sonnar for its optical quality and look. The Zeiss name might help here too. It is kind of a forgotten gem since most young camera users might have never heard about it. It is likely that they know Jupiter or even SONNETAR lenses though. In the photographic world the Sonnar still has its place as a very compact lens with a distinct look. It stands in a line with other names like Petzval, Trioplan or Biotar.
The Sonnar Design
Ludwig Bertele created the Sonnar 5cm f/2 and 5cm f/1.5 in 1932. He described the optical design in his patent of the Sonnar for Carl Zeiss Jena. You can find very detailed descriptions of the Sonnar design online. Marco Cavina talked in depth about the heritage and development of Bertele's Sonnar. Brian Sweeney has written a lot about the character and the design of the Sonnar 5cm. Last but not least zeissikonveb.de has a nice article about all the Sonnar lenses that Ludwig Bertele invented. I'm no expert when it comes to optics but I will try to give you a short overview here.
The Sonnar 5cm f/1.5 is a 35mm / Kleinbild / full-frame lens designed for (Contax) range finder cameras. The optical block is about 41mm long, with a maximum diameter of 44mm, filter size 40.5mm and a weight of 99gr. The distance between the tip of the entry pupil and the film / sensor plane is about 63.5mm. The original optical design consists of 7 lenses in 3 groups in a 1-3-3 configuration. The middle and rear group consists of 3 lenses that are glued together.The use of cemented triplets for front or rear groups is the essence of the Sonnar design. In case of the 5cm f/1.5 both rear and middle group are triplets. Front element and middle group form a telephoto lens. The rear group has a strong collecting effect and forms the final image. The spacings are very narrow and the result is a very compact design with a short back-focus / flange distance. The 2:1 idea of the Sonnar design can be seen in the used triplets too. A triplet consists of 2 collective lenses and one dispersive one.
The design focus of Ludwig Bertele working on the Sonnar design where maximum brightness and contrast by maximum compactness. Working previously for Ernemann and developing the Ernostar greatly influenced the Sonnar design. Alexander Ernemann pushed Ludwig Bertele to create a more compact and even brighter Ernostar 8,5cm that became an instant success. Ludwig Bertele perfected the basic ideas he invented for the Ernostar with the Sonnar. The front element and first triplet of the Sonnar is very much inspired by the Ernostar 8,5cm f/1.8. And even the aperture of f/1.5 might be inspired by his Ernostar 8,5cm f/1.5 concept that was never produced.
To achieve a high brightness for the Sonnar Ludwig Bertele tried to minimize the number of glass to air surfaces. Without anti reflection coating the higher this number the stronger reflections on surfaces reduce the light transmission and brightness of photographic lenses. With the Ernostar Ludwig Bertele invented a solution to reduce the number of glass to air surfaces of lens designs and improve the image quality and brightness. By filling air gaps between lenses with a third lens and cementing them together he could reduce the number of surfaces. The cemented triplet reduces the number of surfaces from 4 to 2. Bertele perfected this principle with the Sonnar design by incorporating the middle lens element as part of the calculation of the whole group to form the previous mentioned 2:1 concept. He achieved this by carefully balancing the used glass and diameter of every lens. With its 3 groups the Sonnar design has only 6 glass to air surfaces just like Triplet or Tessar lenses.
The Sonnar is an asymmetric design. This design choice helped Bertele to achieve a high brightness for his Ernostar and Sonnar designs. By allowing other imperfections he gained more freedom for the final design. The Sonnar design has multiple optical issues like focus shift, field curvature, spherical aberration and coma. Bertele tried not to eliminate but to balance all optical issues in his Sonnar to achieve an image of "perfect imperfections". Many users describe how the image in the viewfinder pops into sharpness when critical focus is achieved. Others describe the 3d effect of taken images. This is thanks of this balance.
The Sonnar 5cm f/1.5 performs best on close focus to mid distance where the bright aperture of F/1.5 can best be utilized. The Sonnar is not balanced for landscape photography. It can be used with good results thought.Bertele's Sonnar design is widely used in a lot of different focal length. 50mm, 85mm, 135mm and 180mm might be the most popular and well known ones. Most of those design where created, calculated and patented by Ludwig Bertele itself. Some Sonnars like 25mm, 40mm, 70mm where only used for very small film formats like Super 8. Others like 150mm or 250mm where used for large film formats. And some designs like the Biogon 35mm are inspired by the Sonnar design.
Manufacturing of Sonnar lenses is quite expensive though. Grinding and gluing the triplets is a very difficult and time consuming task. The tolerances are tight since 3 lenses need to be fitted in a group. Grinding the strong curved diameters is difficult and could only be done in low numbers. The used glass vom Schott was from very high quality and had some unique properties. This all made the Sonnar 5cm f/1.5 an exclusive lens meant for the most demanding photographers.
Compared to the Planar and modern lens designs the Sonnar is in a disadvantage today. The Sonnar dominated the 1930ies and 40ies when anti reflection coating was not available. With single and multi coating, new optical glass and the advance of SLR cameras Planar-type lenses became the standard. Planar based lenses are easier to design and cheaper to manufacture. A main advantage is the high correction of optical flaws that can be achieved. Most customers demand sharp and contrasty lenses with a minimum of optical flaws. Digital cameras with high megapixel sensors expose optical flaws of lenses more easily. Todays lenses have improved to a level where some photographers start to complain about the boring technical perfection of the created images. This advantage has the downside that lenses got bigger and heavier over time. Auto focus motors and a high number of lens elements for correcting optical flaws take a toll. Manufacturers try to counter this by using more digital correction instead optical correction. Issues like vignetting, distortion or even chromatic aberrations are left and corrected digitally by lens profiles.
The Sonnar design is more difficult to design and more expensive to manufacture. Optical correction is not as good as other modern lens designs. When Carl Zeiss released the C Sonnar 1.5/50 2006 they dissolved the middle triplet of the original Sonnar design. The result is a mix of Planar and Sonnar. The C Sonnar gained better optical correction, sharpness, contrast and flare control. It can only be speculated if it was to difficult for Zeiss to improve on the original Bertele design and keep both triplets. To keep only one triplet will make manufacturing cheaper though. The advantage of the Sonnar is its brightness by small size and using a short flange distance.
Digital mirrorless cameras have surpassed SLR cameras for some years now. They use a very short flange distance. This allows to use not only mirrorless lenses but SLR and rangefinder lenses too. By adapting old rangefinder designs like the Sonnar can be used on modern cameras again. In some cases they can even be used with auto focus and stabilization. The result is a very compact and bright digital camera and lens combination. It might not be as compact as the original Zeiss-Ikon Contax and Sonnar 5cm f/1.5 combination but there are not a lot smaller combinations equally bright. Voigtländer's Nokton 1.5/50 Nokton II is the only Planar-type lens that can compete with here. And then there are the MS-Optics Sonnar lenses that are even smaller and brighter. Miyazaki-san recreated his own Sonnar versions with an aperture of f/1.1 and f/1.3. It is open how much the Sonnar design can be optimized by keeping it as small as it is right now. Focusing motors, internal focusing or floating elements would increase the size and defeat the purpose. There is a community of photographers that value size equally like image quality. Others value the imperfection of the Sonnar that can be utilized to create unique images.
Optical Calculations
There are 6 different optical calculations used by Zeiss during the production of the Sonnar 5cm / 50mm f/1,5.
- v1b 1932-10-10 | Ludwig Bertele | 7 elements in 3 groups | max. f/8
- v2b 1932-12-08 | Ludwig Bertele | 7 elements in 3 groups | max. f/11
- v3b 1935-04-15 | Ludwig Bertele | 7 elements in 3 groups | max. f/11
- v4b 1939-08-15 | Ludwig Bertele | 7 elements in 3 groups | max. f/22
- v5b 1951-03-28 | Ludwig Bertele | 7 elements in 3 groups | max. f/16
- v6z 2006 | Zeiss | 6 elements in 4 groups | max. f/16
There exists an even higher number of optical calculations of this lens when prototype lenses are considered. But those will not be handled here.
As can be seen 5 of those 6 calculations where created by Ludwig Bertele himself. 4 of those where calculated back in Dresden at Zeiss Ikon. v5b is not attributed to him officially in literature but Marco Cavina is doing so and in 1951 Bertele was the only person able to proper calculate a new Sonnar design that is using modern glass.
v1b was a big stretch for this time. Diffraction was a big issue so this design is limited to the aperture f/8. Only a very small number of lenses where created. About 155 copies went in production.
v2b shows how much Bertele rushed the first version v1b. After only 2 month he finished a new recalculation with an improved minimum aperture of f/11. It shows the perfectionist that he was not satisfied with the first result. This optics where used for 3 years and in about 6.000 copies.
v3b replaced again the previous optical design. Bertele improved the calculation again and achieved better central sharpness and contrast with this version. This was a quite successful optical design that was used for 3 years in about 29.000 copies.
v4b replaced the third optical design. Bertele probably did this recalculation to incorporate the effect of the T coating. Despite the new anti reflection coating he kept the 2 cemented triplet design used by all previous Sonnars. He was able to achieve a minimum aperture of f/22. This calculation was used by Carl Zeiss Jena (East Germany) until 1960 and about 27.000 copies were made.
v5b was only used by (West Germany) Zeiss Oberkochen. Ludwig Bertele recalculated the design to incorporate the new T coating and glass used by Zeiss Oberkochen. The result is a visible increase in contrast and central sharpness. The minimum aperture is dropped again to f/16. This design was and is still very successful. It was produced until 1959 within about 80.000 Sonnar lenses.
v6z this is a modern optical calculation of the Sonnar 50mm f/1.5 done by Zeiss in 2006. Zeiss pointed out that this design is based on the vintage optical Sonnar design. Probably the starting point of this design was the 1951 Sonnar. This new design is a mixture of Sonnar and Planar design. the frontal cemented triplet was dissolved into single lenses and only the back triplet is kept from the original Sonnar design. The resulting optics combine better correction and flare resistance with high sharpness and contrast. The Sonnar character can still be seen in the final images but it is a little tamed. This lens is still in production today. The exact number of copies is unknown but Zeiss and Cosina manufacturing them in small batches but more then 12.000 were produced.
Since the Sonnar 5cm f/1,5 was copied by other companies after WWII there exist other optical calculations not originated by Zeiss too. One example is the Jupiter-3 production in the former Soviet Union.
- v4b (1948) 1939-08-15 | Ludwig Bertele | 7 elements in 3 groups | max. f/22
- v4k 1954 | M.D. Maltsev (KMZ) | 7 elements in 3 groups | max. f/22
From 1948 until 1954 the Jupiter-3 production used original parts and Schott glass. The Soviet administration started the dismantling of the Carl Zeiss Jena factory very early after WWII and brought almost everything to KMZ near Moscow. This included machines, tools, materials, documents and even hired engineers. This means that KMZ was using finished of half finished lens blocks from German Carl Zeiss Jena or glass from the Jena Schott factory to produce their Jupiter-3 lenses. And they used original design materials and documentation for manufacturing. So it is save to say that the created Jupiter-3 lenses from this time use the v4b optical calculation from Ludwig Bertele. The anti reflection coating used by KMZ differs from the CZJ T coating though. While the T coating shows a brownish tint the KMZ P coating has a yellow tint that is even visible in the final image. How many of those Jupiter-3 lenses were produced is unknown but maybe about 25.000.
In 1954 the supply of Schott glass was exhausted in the Soviet Union. Since Russia has a long tradition in glass manufacturing they opted to replace the Schott glass with local available glass. M.D. Maltsev did a recalculation and created the new v4k optical calculation. This optical design was used until 1988 when the Jupiter-3 production was canceled. Again the number of produced lenses is unknown.
Japanese lens manufacturers adapted the Sonnar design too. They had to deal with similar issues like KMZ. There was no access to Schott glass in Japan and anti reflection coating was still a new technic and difficult to apply. Since after WWII Canon and Nikon did not work together anymore they had to figure out the used glass and calculation all by itself. That their first Sonnar copies did not have a minimum aperture of f/22 might be a hint that they did not use Bertele's 4th calculation but the 3rd. Both manufacturers dropped the original design shortly after to use another improved optical design.
An interesting fact that is overlooked most of the times is that both Russia and Japan where allies years before or during WWII. Russian and Japanese experts and engineers were visiting the Zeiss factory in Jena. They were very interested in the optics and products that were manufactured by CZJ. It is unclear how much knowledge was transferred this way but it might provide a different view on the post-war production of Sonnar lenses.
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