Pekka Buttler, 11/2025
Specifications
The table below summarizes the lens’ key specifications (measurements based on pictured lens):
| Brand: | Carl Zeiss Jena | Lens name | Tessar 4,5/40 |
| Focal length(s)1 | 40 mm | Angle-of-view2 | 57 ° |
| Maximum Aperture | f/4.5 | In Production | 1938–1955 (all variants) 1948–1955 (this variant) |
| Lens mount (this lens) | Exakta | Other lens mounts: | M42, Praktiflex (M40), Praktina |
| Length3 | 34,8 mm | Diameter4 | 60,0 mm |
| Filter ring diameter | 49 mm | Weight | 121 grams |
| Lens element count | 4 | Lens group count | 3 |
| Aperture blades (S/R/C)5 | 10 S | Focus throw | 310 ° |
| Minimum focusing distance (measured) | 38,5 cm | Maximum magnification (measured) | 1:7,45 |
| Has manual aperture ring | YES | Has Manual focus ring | YES |
| Aperture mechanism type | Manual | Aperture click stops 6 | N/A |
Further notes:
• This is a rather small and very light lens, which sports the unusual focal distance of 40 mm (on full frame) and a very dim (f/4.5) maximum aperture.
• This sample is in Exakta mount, but the same lens was also manufactured for the Praktina mount as well as the M42 thread mount.
• The lens has a manual aperture ring (without click stops) and a very deeply recessed front element, so no lens hood is likely necessary.
Historical notes
• Someone might ask: “Why the duck would anyone ever make such a dim lens, with a field of view just barely wider than standard?
• When the Kine Exakta launched in 1936 (not the first SLR, but arguably the to successfully launch the concept) it suffered a bunch of ‘challenges’ (which I discuss at the beginning of this JAPB article), one of the most pressing was “how to allow wide-angle lenses on an SLR”. This was because SLRs (unlike the Leica’s Contax’es and other prime time cameras) were unlike rangefinders in one key respect: The SLR needed to make space for the mirror and shutter arrangement between the lens and the film plane, which also meant that lenses needed to be placed a rather long way away from the film.
• This distance between lens and film (referred to in the circles as “back focus distance”) was no problem for tele lenses or portrait lenses, but it tended to somewhat limit the design of standard lenses (especially fast, standard lenses7) and its almost seemed to be an ‘unmovable object’ (pun intended) with regards to wide-angle lenses.
• This lens was Carl Zeiss Jena’s attempt to stretch the boundaries of the Tessar design (the 1930s most versatile high-IQ design) to allow for a wider field-of-view than the standard fifty. It – quite obviously – suffers some tradeoffs (like the f/4.5) but for many years, this was the only way to achieve anything remotely wide on an SLR.
• The Tessar 40/4.5 was introduced in 1938 and remained the widest lens for an SLR until the 1949/1950 launch of the Carl Zeiss Jena Flektogon 35/2.8 – the arguably first SLR wide-angle lens based on the ‘retrofocus’ concept. The Flektogon however remained out of reach of the amateur audience for quite some time, and the 40 mm Tessar therefore remained in Carl Zeiss Jena’s offering.
• What changed? In 1956 Carl Zeiss Jena’s domestic competitor Meyer-Optik Görlitz launched the 35 mm f/4.5 Primagon [data sheet]. While the Primagon was the Flektogon’s poor cousin in terms of specifications) it was a budget-friendly lens and – compared to the 40 mm Tessar – 5 crucial mm wider.
Versions
Besides having been manufactured for several mounts, there are also three distinct versions of the lens’ design (while the basic optical recipe remained unchanged)
Early: Launched 1938 for the Exakta mount only.
• Short lens that is narrower at the front than at the mount.
• Aluminium construction
• Aperture markings from f/4.5 to F/32
• Minimum focusing distance 0,7m
• At least some lenses marked as “4cm”
Postwar: Launched after the war for Exakta, Praktiflex and M42 mounts
• Short lens that is narrower at the front than at the mount.
• Aluminium construction
• Aperture markings from f/4.5 to F/22
• Minimum focusing distance 0,6m
Late: Launched in the late 40s for Exakta, M42 and Praktina mounts [pictured sample]
• Medium length lens that is barrel-formed (thicker in the middle than at either end
• Aluminium construction
• Aperture markings from f/4.5 to F/16
• Minimum focusing distance 0,4m
History of Carl Zeiss Jena
There are few names in camera optics more illustrious than that of Carl Zeiss. The company was founded in the German town of Jena in 1846 by Carl Zeiß (hence: ‘Carl Zeiss Jena‘). During 1846–1945 there are few major developments in lens optics that the company was not involved in. Names that are even today well-known in optics – such as Planar (1896), Tessar (1902), Sonnar (1929), and Biotar (1939) (as well as many names that only optics-buffs know) – were the product of Zeiss’ first century of technological innovation.
After the Second World War Germany was divided into a Soviet zone (subsequently: East Germany) and the west-allied zones (subsequently: West Germany). While the Zeiss works resided in Jena (optics and glasses) and Dresden (cameras), which were in the Soviet sector, a contingent of Zeiss managers decided to move west and ended up setiting up shop in the small town of Oberkochen in the American sector under the name of Opton Optische Werke Oberkochen GmbH. As the relations between the former allied deteriorated and the split into East and West Germany became all the more real, the Oberkochen works changed their name first to Zeiss-Opton and later to Carl Zeiss.
What ensued was a lengthy international trademark dispute with both Zeiss’ (Jena and Oberkochen) laying claim to the name ‘Carl Zeiss’. The resulting stalemate – emblematic of the Cold War in its entirety – resulted in that Carl Zeiss Opton was allowed to use the name Carl Zeiss in the West, but had to use the Opton brand in the East bloc, whereas Carl Zeiss Jena was the only real Carl Zeiss as far as the east bloc was concerned, but could – mostly – not use the Carl Zeiss -name for exports to the West8. The fact remains however, that – starting in 1946 from a shared base – Jena and Oberkochen developed as two independent companies for more than 40 years. During the entire Cold War period, VEB Carl Zeiss Jena was seen by the country’s leadership both as a paragon of the East German technology industry and a showcase of the socialist/communist system as well as a major source of exports (and hence, western currencies). Within the centrally directed economy’s hierarchy, Carl Zeiss Jena therefore had a more prestigious role than other East German optics manufacturers (prominently Meyer-Optik Görlitz and, later, Pentacon), meaning that Carl Zeiss Jena received privileged access to tools and materiel (including the first computer in East Germany) and that its products were always considered the premium alternative.
After German reunification also Zeiss East and Zeiss West were united again, and have since again been at the undoubtable forefront of lens development. Even though it was manufactured after reunification, this lens sample harkens to the time of the cold-war and the East/West split.
History of the Tessar
The Tessar (together with the Sonnar and Planar) is one of the most famous Zeiss designs. The Tessar – another of Paul Rudolph’s master strokes – first saw the light in 1902 and was – itself – the combination of two earlier Zeiss designs. In essence, the Tessar combines the Zeiss Unar’s (4 elements in 4 groups) and Zeiss Protar’s (4 elements in 2 groups) into a highly compact 4 elements in 3 groups design. This design further has the advantage that it produces a sharp and very well corrected image.
The Tessar, while initially the brainchild of Paul Rudolph, was further developed and refined by a long list of Zeiss’ master lens designers, including Ernst Wandersleb, Willy Merté, and Harry Zöllner. While Willy Merté’s pioneering work proved that the Tessar design can be brought into the range of large aperture lenses (f/2 and better), those feats necessitated the extensive use of aspherical surfaces, which were (and remained for decades to come) not an economically feasible proposition. Instead, it was Zöllner who managed to recompute the basic Tessar design in such a way that allowed raising the maximum aperture to f/2.8 – a design that managed to combine a decent maximum aperture and high IQ into a package that could economically be mass-produced.
Hence, the Tessar remained the weapon of choice for cameras/lenses that did not necessitate a maximum aperture higher than f/2.8. On the other hand, the Tessar’s low group count (compared to Planars and other double Gauss’ designs) also means that the Tessar has a lower number of air-glass interfaces. Before the advent of modern coatings a low group-count approach was much less likely to suffer bad flaring and loss of transmission than a high-group count lens. In fact, even after the introduction of coating technologies, Tessars were customarily sold using less advanced coating techniques.
The combination of high IQ and economic factors made the Tessar the go-to choice for many mid-range cameras, where it played the role of the mid-tier alternative (more advanced than basic triplets; less expensive than Double Gauss designs). Furthermore, as the Tessar could be implemented either as a unit-focusing lens (all elements move to change focus) or – without a significant IQ penalty – as a single-element focusing lens (by shifting the front element vis-à-vis the other elements), the Tessar found use both in interchangeable lens cameras as well as fixed lens cameras.
Various versions of the Tessar were used from their inception in 1902 to their end of production (in the GDR) in 1988. During that time, Tessars were extensively used in many formats (35 mm, medium format, large format) and types of cameras (SLRs, TLRs, interchangeable lens viewfinders/rangefinders, compacts). A testament to the Tessar’s long-lasting fame is that the name is used extensively in lenses (e.g. Tele-Tessar, Vario-Tessar, Smartphone lenses) that share very little if anything with the original Tessar design.
Adapting
n.B! The following applies this lens in either Exakta or M42 mount.
This lens cannot be used natively on any current SLR or dSLRs. To use it in its native environment, you will need an Exakta or M42-mount film body. Luckily there are a lot of those (especially in M42 mount) available.
Thanks to being a fully manual lens (manual aperture, manual focus), the lens can be adapted to all mirrorless cameras using a suitable adapter. Moreover, both Exakta and M42 lenses are so uncomplicated that a simple ‘dumb adapter’ will do the job perfectly. Also, due to the popularity of both mounts, special adapters (helicoid adapters, tilt/shift adapters) are readily available. Alternatively, one can choose to daisy-chain adapters (e.g. M42->Canon EF; Canon EF –> mirrorless) which also opens up a wide range of speed boosters .
Using m42 and Exakta lenses on dSLRs can also be an easy option, depending on which dSLR.
• Canon EF has the shortest flange focal distance among full-frame dSLR’s and Canon’s wide range of dSLRs are able to mount both M42 and Exakta lenses perfectly using a simple adapter ring.
• Minolta / Sony A dSLRs are likewise able to mount M42 lenses using a simple adapter ring, but for Exakta lenses, the difference in flange focal distances is not enough to enable reaching infinity focus without an adapter that uses corrective optics.
• Pentax K dSLRs are likewise able to use M42 lenses using a simple adapter ring, but for Exakta lenses an adapter that uses corrective optics would be needed to allow infinity focus.
• Nikon F dSLRs have a long flange focal distance, meaning that mounting either M42 or Exakta lenses needs an adapter that uses corrective optics to allow anything close to infinity focus.
Footnotes
- Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
- Picture angle is given in degrees (based on manufacturers’ specs) and concerns the diagonal picture angle. Rule of thumb:
> 90 ° ==> Ultra-wide-angle
70–90 ° ==> Wide-angle
50–70 ° ==> Moderate wide-angle
40–50 ° ==> ‘Standard’ or ‘normal’ lens
20–40 ° ==> Short tele lens
10-20 ° ==> Tele lens
5-10 ° ==> Long tele lens
< 5 ° ==> Ultra-tele lens ↩︎ - Length is given from the mount flange to the front of lens at infinity. ↩︎
- Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
- S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
- Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎
- 50 mm had already established itself as the “standard” on 36×24 mm frame sizes, but when the CZJ Biotar – THE fast standard lens for the Exakta – launched, it needed to be designed as a 58 mm lens just to make space for the mirror assembly. ↩︎
- Online one can find many lengthy and heated disputes stating that only Jena/Oberkochen is the true Carl Zeiss. While many of these discussions are riddled with misconceptions and a poor grasp of facts and timings, they largely also tend to be tainted by ideologies. Those discussions that focus on claims of one or the other Zeiss not really having rights to using designs developed at pre-war Zeiss are especially ludicrous because after the war practically the entire patent catalogue of pre-war German patents was given freely to everyone (the allied saw this as a form of reparations), hence also kickstarting the Japanese optics industry’s ascendancy (the Japanese optics companies were the most avid users of German optics patents). ↩︎