Zeiss lenses in the Praktisix/Pentacon Six mount were produced during a period of 35 years: from 1956 to 1991.  Over this period of time, various changes were made to the lenses.   Some lenses were re-calculated during that time, but most were not, so there are two principal differences between most lenses produced during that period of time:

a) stylistic or “cosmetic” changes
 

The very first post-war lenses had a mostly metal-colour finish, with a black leather band on the focussing ring. This 80mm Tessar lens in Praktisix / Pentacon Six mount left the production line on 27th February 1958. Most Zeiss lenses other than the 1000mm mirror lens had the same design style, so when changes of styling were introduced, they were phased in to all other Zeiss lenses.  Meyer-Optik / Görlitz did not follow these style conventions and mostly produced lenses with a black finish during the years that the Praktisix and Pentacon Six were manufactured. When buying any camera with inter-changeable lenses, bear in mind that the lens may not be the one that was on the camera when it was new.  This Praktisix II was manufactured between 1964 and 1966, but the Tessar lens was last produced in the Praktisix mount in February 1958.  It would have been fitted to the original version of the Praktisix. The makers of the Praktisix decided that the camera would sell better if it came with a more prestigious standard lens than the four-element Tessar.  However, we should not forget that at the time the first Hasselblads were also being supplied in many markets with a Tessar lens. For the Praktisix a change was made to the five-element Biometar, which was first produced in the Praktisix mount on 24th March 1959 (earlier versions having been produced for the Rolleiflex and other cameras).  These first 80mm Biometars for the Praktisix had the same cosmetic style as the Tessar illustrated here.
The 80mm Biometar illustrated here was completed on 29th November 1965.  It may well have been supplied on this Praktisix IIA body. For this lens the aperture index ring, the focussing ring and the whole of the filter ring were painted black.  The aperture selection ring was plain metal with red numbers.
Then for a short time a plastic band with bumps on it was used on the focussing ring instead of the leather band. This half-section of a Biometar does not show the serial number – the key to dating Zeiss lenses – but Pentacon Six brochures produced in 1966 and 1967 show lenses with this finish.  It looks as though this particular lens may have been supplied on a late Praktisix IIA. (One 1968 brochure also shows lenses with this finish, but the illustrations must have been made from previous production runs, as the next version of the lens – the famous “zebra” design –  was now in production.)
Then the lenses were designed in the so-called “zebra” finish: mostly black, but with plain metal stripes on the focussing and aperture rings.  (This was approximately 1967-74.)  This 65mm Flektogon was completed on 27 May 1967.
After that the lenses were designed all in black, with a diamond or pyramid-shaped pattern on the focussing ring. Note the feet (red) and metres (white) distance markings on this lens, which was finished on 19th July 1978. Note also the bright metal front edge to the focussing ring.
Later, various changes of style of the all-black lenses were introduced.  This is one of the last Biometars produced.  It was completed on 29 September 1989, about six weeks before the fall of the Berlin Wall, which led to dramatic economic as well as political changes in the GDR. Note the lack of feet markings – export to the U.K. and the USA had long since been abandoned. Notice also that the front edge of the focussing ring is now black.

There was of course also a subsequent version of the 80mm Biometar, but this was not in any sort of Zeiss design; it had the design of the Schneider-Kreuznach lenses that were supplied for the Exakta 66 (1984-2000 version).  You can see pictures of it here.

Note that this is a summary of the main style changes only.

There were also other changes.  For instance, on the 180mm and 300mm Sonnars, the stop-down lever was replaced with a “switch” that could be moved between open-aperture and stopped-down positions, and the barrel of the 300mm Sonnar was re-designed to make it slightly smaller and lighter.

b) Single coating or multi-coating

Starting in 1976, Carl Zeiss gradually introduced multi-coating for all its lenses.  This is easy to identify, as multi-coated lenses are marked “MC”.  In the early years of the change, these letters were in red paint, but from about 1980 onwards, the letters “MC” were usually in white paint.

If you see two equivalent lenses, but one is single-coated and the other is multi-coated, I would of course recommend the multi-coated lens, which will be newer.

c) Optical Re-calculation of lenses

Various lenses with the Praktisix/Pentacon Six mount were optically re-calculated over the period of many decades during which they were produced.  One example is the 80mm Biometar.  The original version of this lens in the Praktisix/Pentacon Six mount was calculated on 5th June 1956, although the first batch of this lens in what was at the time called the Praktisix mount was not produced until 24th March 1959.  Over the following 30 years, almost all of the 80mm Biometars that were produced used the 1956 calculation.  However, on 31st October 1979 the 80mm Biometar was re-calculated.  Nevertheless, even after this date most of the 80mm Biometars produced were to the original calculation.  Ten years later, on 29th March 1989, just one batch of 6,000 80mm Biometars was produced using the new calculation.  The serial numbers of that batch are 42,001 – 48,000

Here is a summary of the design dates of Carl Zeiss lenses in the Praktisix/Pentacon Six mount.  However, as will be obvious from the preceding paragraph, sometimes even after a new design was calculated, the lens continued to be manufactured to the previous design, and sometimes even after batches made to the new design were produced, some subsequent batches were made to the previous optical design.
 

(1)  The Tessar had of course existed for decades before a version was calculated for use with the German post-war medium format cameras.
(2)  It is of course well-known that this lens was first calculated and designed for the 1936 Berlin Olympics, where it was used on a 35mm Contax rangefinder camera.  However, the first version that was manufactured in the Praktisix/Pentacon Six mount was the February 1959 re-calculation.

Reasons for re-calculating lenses

It should be borne in mind that there could be various motives behind a re-calculation, and one must not automatically assume that a newer calculation must be optically better; the purpose of the re-calculation might be to reduce weight, as in the case of the 300mm Sonnar.

Changes in other requirements could also lead to design changes.  Thus, for example, the first design of the two Sonnars for the Praktisix/Pentacon Six incorporated automatic micro-adjustment of the diaphragm diameter as one focussed closer, to compensate for the slight reduction in light transmission to the film as the barrel length was increased by focussing closer.  (As one focussed closer, the diaphragm opened progressively.)  Two factors led to the removal of this feature when the lenses were re-designed:

• the improved exposure latitude of colour film
• the provision of through-the-lens metering on the Pentacon Six, with the introduction of the metering prism.

Optically, all of the Carl Zeiss lenses are excellent.  The mechanical condition depends on whether the lens has been looked after or badly-treated by a previous owner – for instance, if it has been dropped or taken apart by someone who does not understand lenses.

Fortunately, it is possible with the help of the serial number to date most of the lenses that Carl Zeiss, Jena produced and there is a book that gives detailed information on the date of design and manufacture of Carl Zeiss lenses, based on the serial number.  This book is Dr Hartmut Thiele’s “Fabrikationsbuch Photooptik II Carl Zeiss Jena”, which lists most Carl Zeiss Jena lenses manufactured between 1927 and 1991.  I recommend this book to anyone who wants to go into the details of Carl Zeiss Jena serial numbers.  The book costs about 50 Euros. Batches of serial numbers were apparently assigned to the production department in Carl Zeiss, Jena in sequence order.  i.e., if the last lens in the previous batch of lenses had the number 8,000,000, the first lens in the next batch would be given the number 8,000,001.  However, sometimes the production department did not make the batches in the same order as the serial-number blocks that had been assigned to them.  Thus, for example, a batch of 5,000 80mm Biometars was assigned the serial-number block 10,890,988 – 10,895,987 and this batch was finished on 2nd September 1980.  The previous block of 5,000 serial numbers (10,885,988 – 10,890,987) had also been assigned to a batch of 80mm Biometars, but this batch was not completed until six months later, on 28th February 1981.  However, in spite of details of this nature, serial numbers are a good guide to the age of a lens. In the example above, I have added commas here, to make the numbers easier to read, but no commas, full stops or spaces were used when the serial number was engraved on the lens, unlike the practice of Schneider-Kreuznach, who put spaces where I have put commas. By mid 1980, Carl Zeiss had reached the serial number 10,982,372 (nearly 11 million).  It then decided to start the serial numbers anew, apparently beginning at 1,0001 (although there are very small numbers of lenses produced in the 1980’s with lower numbers than this).  So most lenses made between about mid 1980 and 1991 had four or five-digit serial numbers and are therefore the newest lenses.  (You can see from the example given above that some of the lenses with serial numbers in the ten millions were in fact not completed until early in 1981.)

Hartmut Thiele’s book on Carl Zeiss Jena lenses

A wide range of Carl Zeiss Jena lenses in Praktisix/Pentacon Six mount are illustrated and tested in the Lens Test section of this website.  To go to the lens test section, click here.

To see some information on camera body variations and dates, see here.

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