Data sheet: MIR-26b 45 mm f/3.5 (Pentacon 6)

Pekka Buttler, 02/2024

Pictured: MIR-26b (Мир-26Б) 45 mm f/3.5 with a Pentacon 6 mount (sample shows minor signs of ‘Schneideritis‘)


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

Brand:MIRLens name28b 3.5/45
Focal length(s)145 mmAngle-of-view284 ° (on medium format)
≈51 ° (on ‘full frame’)
Maximum Aperturef/3.5In Production1970–≈1995 (all mounts)
1974–≈1995 (this mount)
Lens mountPentacon 6Other lens mountsKiev-88
Length377,5 mmDiameter485,2 mm
Filter ring diameter82 mmWeight588 grams
Lens element count8Lens group count7
Aperture blades (S/R/C)56 S 6Focus throw120 °
Minimum focusing distance50 cmsMaximum magnification1:9,0
Has manual aperture ringYESHas Manual focus ringYES

Further notes:

• This lens was designed and manufactured for use on medium format (6×6) cameras.
• These lenses were manufactured in modern-day Ukraine for both the Salyut/Kiev-88 and Kiev-6n (Pentacon Six) systems. Some aftermarket modifications exist to use this lens on other medium format systems.
• This was the widest-angle rectilinear lens offered for both the Pentacon Six and Salyut/Kiev-88 systems. With a focal length of 45 mm its diagonal angle-of-view is 84°, which corresponds to a 24 mm focal length on ‘full frame’. However, angles-of-view are not easily comparable between frames of different dimensions (1:1 on medium format; 3:2 on ‘full-frame’)
• With its bulky, fluted design, the lens clearly is a representative of an earlier-generation of wide-angle lenses. Not surprisingly, a modernised version of the lens (the Mir-69 45mm f/3.5) was in the works, but in the closing moments of the Soviet Union, it never reached serial production.
• Because of the largish 82 mm filter thread, these lenses were typically supplied with a custom set of filters (UV and green).
• After the fall of the Soviet Union it seems that the Arsenal plant assembled some more copies of the lens and – at least according to one source – sold them under the ‘Arsat’ name. However, I have never seen a sample labeled Arsat in the wild. If someone has concrete information, I would welcome them getting back to me.
• The usual sources indicate that production of the MIR-26 ended in 1992 or 1993. However, I’ve encountered a number of samples with serial numbers starting with “95”. These lenses are outwardly similar to lenses from 91-93, and do not carry the name “Arsat” on the lens. I deduce that we’re dealing with samples put together from parts stocks.

• As an added note: I usually do not comment on the quality (optical or otherwise) of a lens in these data sheets, but I feel I have to make an exception here. I have three samples of this lens (dated between 84-87), and all suffer the same problem – an inoperative aperture stop-down mechanism. Moreover, in all three cases the same minuscule metal component of the stop-down mechanism has broken in a way that leads me to suspect that the component has been subpar from before it was mounted in the lens. If your only intention is to use the lens adapted, this might not be an issue, but if you intend to mount the lens on a film camera, make sure that your copy has a working aperture mechanism.
• Maybe related to a poor parts quality of lenses, I have seen (on eBay and other classifieds= a large share of ‘Frankenlenses’ – lenses that clearly are the result of mixing & matching parts, assumedly done by repairmen. The most blatant (and easily spotted) form of such combining is to be found whenever one encounters a lens that has one lens mount, but the name ring would indicate that the lens should have another mount (one of my samples is a lens that has a Pentacon Six mount, but the name ring says it should be a Kiev-88 mount). Hence, I would also take serial numbers with a grain of salt…


It would seem that the optical design of the lens stayed the same throughout the 20+ years of manufacture. However, the ergonomics did progress somewhat.

Version 1: 1970–?
The earliest samples (at least until 1975) featured a metal focus ring with lengthwise milled ridges.

[I have not seen a single sample manufactured between 1975 and 1982 and can hence not offer a guess on when the focus ring was redesigned]

Version 2: ? – 1990
At least starting from 1982 the focus ring grip featured a knurled, metal pattern (as in the sample above)

Version 3: 1991->
Starting in 1991 the focus ring was rubberised with a quadratic pattern.

Also, existing source point to that some of the lenses were manufactured at Arsenal’s main plant in Kiev (Ukraine), while others were manufactured at the Vega plant in Uman (Ukraine). Some online comments indicate a lower confidence in quality control at the Vega plant…


If you’ve come into possession of this lens, your sample will either have a Pentacon 6 mount, or a Kiev-88 mount. Here I will discuss adapting the lens in Pentacon 6 mount, but the same principles apply to a lens with the Kiev-88 mount.

To use this lens natively, you will need a Pentacon 6 mount film body. In practical terms this means either a Praktisix or Pentacon Six medium format film camera or a Kiev 60/6C medium format film camera. While neither of these families of bodies were manufactured in their millions, they remain readily available, and even serviceable.

Thanks to the generous image circle Pentacon 6 lenses offer, and thanks to the copious flange focal distance (74,1 mm) of the Pentacon 6 system, this lens can be adapted to every full frame (and smaller) SLR, dSLR and mirrorless camera assuming a suitable adapter can be found or manufactured. Moreover, Pentacon 6 lenses are so uncomplicated that a simple ‘dumb adapter’ will do the job perfectly.

Thanks to the generous image circle, Pentacon 6 lenses have also long been a strong candidate to be used on smaller formats (full frame and smaller) in conjunction with tilt/shift adapters. Alternatively, one can choose to daisy-chain adapters (e.g. Pentacon 6->Canon EF; Canon EF –> mirrorless) which not only broadens the range of available adapters, but also allows using speed boosters for those photographers that use smaller than full-frame sensors.

Finally, regarding larger than full frame, there are also options. Digital medium format is perfectly usable (assuming adapter availability) and many 6×4,5 film formats are likewise theoretical possibilities, but gaining functional adapters may necessitate some DIY.


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.

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