Data sheet: Jupiter-6

Pekka Buttler, 01/2026

This lens was kindly provided for cataloguing by Vladimir at #photogears

Specifications

The table below summarizes the lens’ key specifications (measurements based on pictured lens):

Manufacturer:	KMZ	Lens name	Юпитер-6-2 / Jupiter-6-2 2.8/180
Focal length(s) 1	180 mm	Angle-of-view 2	14 °
Maximum Aperture	f/2.8	In Production	1948–≈? (all variants)
Lens mounts (this lens)	M42	Other lens mounts	Z39
Length 3	132,2 mm	Diameter 4	95,0 mm
Filter ring diameter	77 mm	Weight	1476 grams
Lens element count	5	Lens group count	3
Aperture blades (S/R/C) 5	10 S	Focus throw	310 °
Minimum focusing distance (indicated)	2 m	Maximum magnification (calculated)	1:9
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Preset	Preset click stops 6	2.8-4-5.6-8-11-16-22

Further notes:
• The Jupiter-6 is a Soviet version of the Carl Zeiss Olympia Sonnar 180/2.8 (Introduced 1932).
• From the early 1950s versions for soviet SLRs (Z39) was introduced. Later, as Soviet SLRs shifted from the Z39 to the M42 mount, also a version for the M42 mount was made.
• The aperture is a preset aperture. The aperture ring is clickless, but the preset ring locks only on specific positions (See above).
• Because Soviet production of the Jupiter-6 started with parts taken as war reparations from Germany, the optical design was somewhat unstable in the early years. After the first few years, all parts were Soviet-built.
• The lens was single-coated from the onset, but at some stage in the 1960s multicoating was introduced.
• I have not managed to find conclusive information of when manufacture of the lens was ended.
• The pictured sample is a prototype (serial starts with 00), but a rather late prototype. Whether this lens was manufactured to test the black finish on the Jupiter 6-2 or some other aspect, I am not certain.

• The pictured lens has another quirk in that its aperture scale and focus scale do not align. The lens’ owner speculated that this sample had at some stage been modified for cinematographic work (so that the distance scale would be easily readable to the focus puller).

History of Jupiter and other Soviet lenses

If you’re interested, I recommend you read JAPB’s article about the Soviet lens ‘business’.

History of the Sonnar designs

The Sonnar designs were originally born out of necessity. Back before the invention of lens coating technology, each air-glass boundary represented a serious problem. Every air-glass boundary meant roughly 5% of the light that would hit such a boundary would be bounced back, instead of passing through the boundary. This not only meant that each air-glass boundary would decrease the amount of light that passed through the lens to the film plane, a goodly portion of that reflected light was liable to be bounced around within the lens, leading to veiling flare and loss of contrast. Hence, design a lens to minimise the number of lens groups was crucially important.

Until the invention of the Sonnar design, the only ways to produce large aperture lenses were based on the double-Gauss (a.k.a. Planar) and Ernostar designs, both of which were hampered by that the number of air-glass boundaries were relatively high (a minimum of 8). The Ernostar was the 1924 creation of the young (then only 23 years old) lens designer Ludwig Bertele for the company Ernemann. At the time of its launch it was – at f/2 – the fastest still camera lens in existence, and one year later Bertele bested his previous record with the f/1.8 Ernostar.

After Carl Zeiss acquired Ernemann in 1926, Ludwig Bertele continued pushing the boundaries and the Sonnar was a further development of the Ernostar. Not only did the Sonnar in 1932 manage to achieve an even larger maximum aperture (at f/1.5), it did so while simultaneously decreasing the number of lens groups to 3 (hence decreasing the number of air-glass boundaries to 6). It seemed like the perfect solution.

Bertele developed a range of Sonnar-based designs: Standard lenses for rangefinder cameras (that did not necessitate a long back focal length) and tele lenses (for both rangefinders and SLRs). Some of those tele lenses were relatively ‘ordinary’ in their headline specifications (e.g. 135 mm f/4) but ahead of other contemporary lenses in their image quality, whereas other designs were clearly aimed at producing exceptionally bright tele lenses (such as the 85/2 or 180/2.8).

Adapting

This chapter will discuss adapting the Z39 and M42 versions of the lens.

Adapting Z39 version

If you want to adapt a Z39 mount version of this lens, you have two options:

The easiest approach is to buy a Z39->M42 adapter ring and then treating the lens as if it was a M42 mount lens. While simple, and — theoretically – opening the door to adapting the lens also to some dSLR mounts (Canon EF, Pentax K), there is a possible problem in that the flange focal distance of the Z39 mount (45,2 mm) is ever so slightly shorter than that of the M42 mount (45,46 mm). This might therefore lead to your lens’ depth of field not quite reaching infinity unless you stop down a bit.

The other approach is to use a 16,4 mm long M39-thread extension tube to bridge the gap from Z39 to the Leica thread mount (LTM; 28,8mm) and then going from there to your mirrorless mount. While this does not allow adapting to SLRs, it is rather elegant. Eh?
Where – you might wonder – is one to find such a specific extension tube? Due to the fact that the Soviet lens industry was manufacturing both Leica thread mount cameras (FEDs and Zorkis) and Z39 SLRs (early Zenits), pretty much every soviet LTM/Z39 extension tube set contains an extension tube of that precise length 😉

Adapting M42 version

If you want to natively mount an M42 lens you need to find a functioning M42 mount film camera. Luckily that should be relatively easy as M42 bodies were produced in their millions and most of them lack features that are especially likely to have deteriorated to the point of making the entire camera inoperable. If your sample of this lens offers a switch to choose between auto- and manual aperture, I recommend using the lens on a body that is capable of stopping down the lens automatically and offers stop-down metering.

Adapting this lens to a mirrorless, full-frame digital camera is a breeze thanks to the lens having full manual controls (aperture ring, focus ring). You simply need a dumb adapter from M42 to your mirrorless system.

Due to the medium flange focal distance used by the M42 mount (45,46 mm), whether you can adapt this lens to dSLR/SLR mounts depends on which dSLR mount: Canon EF, Four Thirds, Minolta/Sony A and Pentax K can mount m42 lenses using a simple adapter ring. Nikon F on the other hand is not as problem-free, and – to retain anything near infinity focus – the adapter will necessitate corrective optics. In all cases, your camera will work only in stop-down metering.

Footnotes

1. 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’. ↩︎
2. 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 ↩︎
3. Length is given from the mount flange to the front of lens at infinity. ↩︎
4. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
5. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
6. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎