The Pentacon Six System
by TRA

The 80mm standard lenses in Exakta 66 style

Remarkably, four different 80mm lenses were offered for the Exakta 66 (1984-2000 model).


Xenotar MF or E?
There were two types of Schneider Xenotar in Exakta 66 mount: the original lens, which is designated “MF” in the literature and on the lens ring, and a newer, cheaper lens, designated “Xenotar E”.  See details of the “Xenotar E” below.  The Schneider Xenotar MF was manufactured by Schneider-Kreuznach for a range of leading camera manufacturers, including Rollei, and is considered is one of the world’s top standard lenses for medium format.  Many consider it superior to the Planar made by Carl Zeiss (Oberkochen, former West Germany) for the Hasselblad.

Who made the 80mm Biometar lens in Exakta 66 style?
It is stated by some vendors that this version of the Carl Zeiss Jena Biometar was manufactured in the Joseph Schneider factory.  However, evidence is contradictory.
It is true that the external design matches that of the Schneider lenses for the Exakta 66.  My lens, which was bought new, also came with a Schneider Kreuznach lens cap. 
However, this is hardly conclusive.  Most of the lenses for the Exakta 66 were designed to take 67mm filters, and Schneider must have produced very large numbers of lens caps to fit on all these lenses.
The Biometar lens ring states “Carl Zeiss Jena”.

I am also grateful to Donggil Lee of Seoul, South Korea for drawing my attention to the fact that the colours of the Multi Coating on this version of the Biometar “are more like those of M42 Carl Zeiss Jena lenses than those of Schneider lenses including Schneider Exakta 80mm lens and Xenotar 80mm lens”.  I have checked with my examples of these lenses, and can confirm these differences:  the Xenotar MF and Exakta 80mm lenses have a deeper purple in the multi-coating, while the Biometar has a lighter, pinker colour, although this is not at all like the amber colour multi-coating on the 80mm MC Biometar that came with one of my Pentacon Sixes (unequivocally from East Germany) in the mid 1980s.  However, later East German Biometars had a different, light purple multi-coating.

There is another interesting fact that does seem to point conclusively to this lens not having been manufactured by Joseph Schneider: the serial number.  In January 2006 I came across a database of serial numbers for Joseph Schneider lenses.  It can be seen at, part of Schneider Kreuznach’s own website, and therefore presumably authoritative.
This website shows that all Schneider lenses manufactured between October 1983 and January 2002 (the latest month for which they give data) have numbers in the 14 millions, i.e., 14 xxx xxx, where the x’s = other numerals.  I can confirm that all my Schneider lenses manufactured for the Exakta 66 have serial numbers in the 14 millions (and some other Schneider lenses that I have for other equipment have serial numbers that tally very well with the periods when I bought them).

But my Biometar in Exakta 66 style has a five digit serial number beginning with 48 – i.e., it is in the 48 thousands.  Hartmut Thiele’s excellent reference work “Fabrikationsbuch Photooptik II Carl Zeiss Jena” is an authoritative source on Carl Zeiss Jena serial numbers, and it shows that in the last months of the GDR Carl Zeiss Jena manufactured 6,000 80mm Biometar lenses – naturally in the standard Pentacon Six style – and the serial numbers ran from 42001 to 48000.  These lenses were made using the newer, 1979, lens re-calculation.  They were completed on 29th March 1989.  I originally believed that these were the last 80mm Biometars that were produced in the Pentacon Six style.


However, six months later (on 29th September 1989), a batch of 5,000 80mm Biometars were finished that had been made using the old (1956) calculation.
  These lenses had serial numbers from 37001 to 42000 and it is this batch that is listed in Thiele as being the very last 80mm Biometars to be completed in the Pentacon Six style.  Interestingly, the serial numbers of this batch are immediately before the serial numbers of the batch finished six months earlier that used the newer, 1979, calculation.  This does confirm the evidence from elsewhere that batches of serial numbers were supplied to the production department, but that sometimes it did not complete the corresponding batches in the order that might be implied by the serial numbers.
Correction added 18th October 2016.

By the time the Biometar lenses in Exakta 66 style were being manufactured, all sorts of deals were being done between former East German and West German companies, with Carl Zeiss Oberkochen (former West Germany) buying parts  – but not all! – of Carl Zeiss Jena, and Schneider Kreuznach linking up with at least parts of Pentacon.

It is thus clear that at least the optical elements of the Biometar lenses in Exakta 66 style were manufactured by Carl Zeiss Jena, possibly with serial numbers starting with number 48001.
It seems probable that the barrels for this batch of lenses were supplied to them by Schneider-Kreuznach.

It seems to me that these lenses were almost certainly manufactured in 1990, during the inital phase of co-operation between East and West German firms, after the breaching of the Berlin wall in November 1989.
I have not been able to discover whether this Exakta 66 batch was based on the 1956 calculation or the newer, 1979 calculation.
If Schneider were aware of the two different calculations, it is reasonable to assume that they would have requested that the newer calculation be used.

Additional information added 18th October 2016.

This version of the lens is physically much larger than the original Biometar, with the front extending much further forward and out, to accommodate the standard-size 67mm filter that fits many of the Exakta 66 lenses.  Some users report that in consequence of this, a lens hood (“shade”) is not really necessary with this lens.  To see earlier versions of the 80mm Biometar in Praktisix/Pentacon Six mount, click here.

Xenotar E
Externally, this is identical to the Carl Zeiss Jena Biometar that was made in Exakta 66 style – the dimensions, weight, minimum focussing distance and labelling and spacing of the focus distances printed on the lens are identical.  Even the location of the screw-heads on the back of the lens are identical.  Crucially, the “Xenotar E” that I have seen has a five digit serial number beginning with 48 – i.e., it is in the 48 thousands – exactly the same as the Biometars manufactured in Exakta 66 style!

Some claim that this may have been a re-labelled Biometar manufactured by Schneider.  However, serial number evidence indicates that these lenses were almost certainly part of the same batch as the Biometars in Exakta 66 style.  Perhaps the only thing changed was the name ring on the front of the lens, a trick that Carl Zeiss Jena were experienced in using, in order to export to certain countries where they were not allowed to use the Carl Zeiss name.

One thing, however, is different: the multi-coating (see below).

“Exakta” 80mm lens
It appears that this lens was manufactured by Joseph Schneider.  The design matches that of the Schneider lenses for the Exakta 66, and my lens, which was bought new, came with a Schneider Kreuznach lens cap.  Its serial number follows Joseph Schneider conventions used with other lenses for the Exakta 66.  It is in the 14 millions, with a number that would appear to indicate that it was manufactured in January 1991, which sounds about right.  Some sources indicate that this lens is in fact optically a Biometar, but manufactured now by Schneider, with of course their coating and serial numbers.  Examination of the lens indicates that this is probably the case.  The front of the lens barrel has been extended forward, to make it look more like the original Xenotar MF.  This adds a small amount to the weight, in comparison with the Biometar in Exakta 66 style, and also enabled the close-focussing range to be increased fractionally.

Comparison of the 80mm standard lenses in Exakta 66 style

Left to right: Xenotar MF, Biometar, Xenotar E, Exakta

Here is a summary of the similarities and differences between these four lenses.

Name on lens ring: Schneider-Kreuznach Xenotar MF Carl Zeiss Jena Biometar Schneider-Kreuznach Xenotar E Exakta
Minimum focussing distance m: 0.6 1.0 1.0 0.95
Dimensions (dia × length) mm: 84 × 72 82 × 68 As Biometar 83 × 74
Weight g: 500 440 As Biometar 450
Location of rear-most element: Deeply recessed Protruding from rear surface As Biometar As Biometar
Rear element retaining ring: Deeply recessed Protruding above rear surface.  Scalloped on top edge to allow mirror to pass (as on Biometars for the Pentacon Six) As Biometar As Biometar
Pin heads visible on rear surface: Two black pins Three “silver” pins (as on Biometars for the Pentacon Six, in which, however, one of the pins is black) As Biometar As Biometar
Stop-down lever: Wide sliding black bar under lens – as on other Schneider lenses for the Exakta 66 Tiny “silver” lever at approximately “7.00 o’clock” (as on Biometars for the Pentacon Six) As Biometar As Biometar
Raised lettering on front surface of rubber focussing ring: SCHNEIDER-KREUZNACH
As Biometar As Biometar
Multi-coating name: MULTICOATING S MULTICOATING As Xenotar MF As Biometar
Multi-coating colour: Slightly less deep purple than “EXAKTA” lens Lighter than “EXAKTA” & “XENOTAR MF”, almost pink Totally different from the other three – a light amber-yellowish colour Deep purple reflections
Serial number range: 14 millions 48 thousands As Biometar 14 millions

Left to right: Xenotar MF, Biometar, Xenotar E, Exakta, plus, to the right of them, the CZJ Biometar in Pentacon Six styling
Note that when the Biometar was made in Exakta 66 styling, it was necessary to reverse the direction of the aperture ring,
to enable it to input the correct values into the Exakta 66 metering prism

Rear view (lenses arranged in the same order)
Note the differences between the Xenotar MF, on the left and all other four lenses, as regards pin and screw positions, shape of stop-down lever, etc.

Note shape of the rear element retaining ring, scalloped at the top on the all lenses other than the Xenotar MF to allow clearance for the mirror.
It is also clear in this image that the rear element of the Xenotar MF is recessed within the mount.

Summary of Multi-coating differences
All four 80mm lenses are different from each other.
The “EXAKTA” lens has the deepest purple reflections.
The “XENOTAR MF” has slightly less deep purple reflections.
The BIOMETAR has lighter-still reflections, almost pink.
The “XENOTAR E” has a totally different colour from the other three – a light amber-yellowish colour similar to but deeper than that seen on some East German Carl Zeiss Jena lenses for 35mm cameras.

The aperture blades of all four of these lenses have a virtually-identical matt-black finish, quite unlike the shiny black surface of the aperture blades on the Biometars built by Carl Zeiss Jena in GDR times.  It is clear that after the fall of the Berlin Wall and the collapse of communism in East Germany in November 1989, there was considerable exchange of technical expertise (and possibly of some parts?) between the Schneider-Kreuznach and Carl Zeiss Jena.  It is also possible that components may have been sourced from more than one manufacturer, for instance, the lens elements in Jena and the barrels (and assembly?) in Bad Kreuznach.

Reconstructing History

FACT:  The Exakta 66 was launched in 1984 with the Schneider-Kreuznach Xenotar MF as the only standard lens available.  This outstanding lens had a high price, which was reflected in the Exakta 66 outfit price.
FACT:  At the time, both Schneider-Kreuznach and Exakta GmbH belonged to the German industrialist and entrepreneur Heinrich Mandermann, whose company had for many years distributed Carl Zeiss Jena lenses in West Germany.
FACT:  Exakta 66 sales were substantially below the hopes of Heinrich Mandermann and the others who brought the outfit to the market.
FACT:  A matter of weeks after the collapse in November 1989 of the Berlin Wall, in 1990 Carl Zeiss Jena Biometars in Exakta 66 “livery” were offered as an alternative to the Xenotar MF, at a much lower price than the Xenotar MF.

The rest of this box is SURMISE.

The aim was obviously to boost the sales of the whole Exakta 66 system.

I surmise that offering the Carl Zeiss Jena Biometar did not achieve this aim, and that Exakta GmbH decided to avoid buyer resistance to buying an “East German” lens by relabelling the Biometar “Xenotar”.
This would have been at best misleading to the public (and it continues to mislead people to the present day, hence the high prices that the “Xenotar E” fetches at auctions).
I therefore surmise that it was decided to name the lens “Xenotar E”, with the “E” standing for “Exakta”.

I surmise that:

  • this new step failed to convince the market (we do know that sales did not pick up), and that 
  • some knowledgeable traders and users of the real Xenotar (for instance, on Rollei medium format cameras) objected to the use of the Xenotar name on a lens that was not a Xenotar and objected to the use of the Schneider-Kreuznach name on a lens that was not made by Schneider-Kreuznach.
I surmise that in response to this, Schneider-Kreuznach concluded that their brand might be damaged if confidence in the company name and the lens name were undermined, and that they therefore decided to do three things:
  • Stop using the Xenotar name on the Biometar lens
  • Stop using the Schneider-Kreuznach name on the Biometar lens
  • Re-design the front of the lens barrel, lengthening it so that it superficially ressembled the original Xenotar MF lens more closely and its parentage as a Biometar was less obvious.
At the same time, Carl Zeiss Jena was being broken up with parts being sold to various western companies (including Schneider-Kreuznach and Carl Zeiss West Germany).

I therefore surmise that Schneider-Kreuznach either decided to or had to manufacture the lens themselves.  This new version of the lens was given the name “EXAKTA”, but was in fact still optically the original Biometar lens.

New information, January 2010

The above section was written in March 2009.  I have just (January 2010) obtained a copy of the lens diagrams for the “Biometar” and “Exakta” lenses in the Exakta 66 livery.  They were contained in a catalogue of photographic items distributed in Germany by the firm Beroflex.  This catalogue was produced for their own company reps only, not for public distribution, and included details of Praktica cameras and lenses and other ranges distributed by Beroflex, including the Exakta 66.  The catalogue is dated March 1992 – after the re-unification of the two Germanies and at a time when the Exakta 66 was still being marketed.  In the latest endeavour to boost sales of the Exakta 66, the “Exakta” 80mm lens had been introduced.  Here is a section from one of the pages:

I have added on the left an English translation of the title for each line.  It is clear that the data is the same for both lenses, except for the two points referred to above: the front of the “Exakta” lens has been made longer/deeper, and this has naturally increased the weight slightly.
Here are the lens diagrams only, in a larger size to make them easier to compare:

I have added grey to the lens elements, to make them easier to distinguish from the lens body.  It is clear that optically this is the original Biometar 5-element design as supplied for the Pentacon Six.  The company reps were presumably given this information to enable them to decide how much detail to share with retailers, when promoting the Exakta 66 system.

Conclusive evidence

Having used the barrel of an 80mm “Exakta” lens for the mounting of the 40mm Schneider Curtagon (details here), I had a spare set of “Exakta” elements.

Then I came across an 80mm Biometar lens in “zebra” style, in excellent condition apart from scratches to the front element and dirt between the elements.  I asked Tom Page if he could mount the “Exakta” elements in the Biometar mount.  They fitted perfectly!  In fact, one can see that they are of the same design.

Another lens that is probably unique in the true sense of the word.
This “zebra” Biometar now has multi-coated elements, whereas all the Carl Zeiss Jena zebra lenses had single coating only.


I am grateful to Rick Denney for drawing my attention to the fact that this is the same as the original formulation of the Schneider-Kreuznach Xenotar, as patented in various countries in 1952 and used in the Rolleiflex and other medium format cameras.

The original formulation of the Schneider-Kreuznach Xenotar had five elements.  Later versions of the Xenotar had six or seven elements.  The Xenotar MF as supplied for the Exakta 66 and various other Medium Format SLRs in the 1980s had 7 elements in 6 groups.

Now it would be good to see the lens diagram for the “Xenotar E”!  It might be reasonable to guess that it will be the original 5-element design – in other words, equivalent to the Biometar or the “Exakta” whose design is shown above.

Rudolf Kingslake states in “A History of the Photographic Lens” that this original formulation of the Schneider Xenotar is the same as the (West) German Zeiss Planar that was produced after World War II.

The original formulation of the
Schneider-Kreuznach Xenotar (c. 1952).

However, this drawing that is reported as being of the original 5-element Carl Zeiss (West Germany) Planar lens as installed in the Rolleiflex Twin-Lens Reflex in the early 1950s shows a different configuration of the front three elements.

As with the Schneider Xenotar, subsequent designs of the Zeiss Planar had six elements, and then seven elements.

(The Rolleiflex TLR was available with a choice of taking lens.)

From “A lens collector’s Vademecum”

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© TRA March 2009.  Latest revision: August 2017