Data sheet: Industar-50

Pekka Buttler, 07/2023

Specifications

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

Manufacturer:	KMZ (Krasnogorsky Mekhanichesky Zavod)	Lens name	Индустар-50 / Industar-50 3,5/50
Focal length(s) 1	50 mm	Angle-of-view 2	45 °
Maximum Aperture	f/3.5	In Production	1953–≈1985 (all variants)
Lens mount (this lens)	Leica thread mount	Other lens mounts	Z39, M42
Length 3	36,7 mm	Diameter 4	49,8 mm
Filter ring diameter	33,5 mm	Weight	102 grams
Lens element count	4	Lens group count	3
Aperture blades (S/R/C) 5	7 S	Focus throw	160 °
Minimum focusing distance	0,9 m	Maximum magnification	1:15,2
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Manual	Aperture click stops	None (clickless)

Further notes:
• Besides the Industar-50 (LTM and Zenit M39), there is also the Industar-50-2 (M42). Optically they are all very closely related.
• The Industar-50 is a 4 elements in 3 groups (Tessar) design.
• There was both an ordinary as well as a retractable version of the Industar-50.
• The aperture ring is clickless and fully manual. Moreover, the aperture ring is placed in a rather awkward position (on the front of the lens). These two conspire to make it practically impossible to adjust the aperture without taking your eye form the viewfinder and rotating the camera until you can read the aperture value.
• To add insult to injury, not only the filter threads rotate when focussing, but also the entire aperture adjustment apparatus.
• The Industar-50 was manufactured by a wide range of factories, including KMZ (this sample), LZOS (Лыткаринский завод Оптического Стекла), and KOMZ (Казанский оптико-механический завод).
• Regarding the retractable version, a common worry is whether it might damage the sensor. Those who harbour such worries should remember that it was designed to touch neither the film nor shutter curtain of the cameras it was used on. Hence, unless the lens is damaged, it should not be able to touch the sensor.

History of Industar and other Soviet lenses

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

History of the Tessar designs

The Tessar 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 relatively compact 4 elements in 3 groups design.

In its day, the Tessar had a lot going for it: Firstly, it was a design that was able to address the critical ≈45° angle-of-view (what we tend to call standard lenses). Second it was known to be able to offer sharpness and good aberration-correction (which preceding designs were not known for). Moreover, it was able to use a relatively low group count (3), which – especially prior to the development of modern coatings – meant that it was less likely to suffer bad flaring. Furthermore, it 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). This ability made the Tessar especially attractive in both folding cameras and TLRs. On the other hand, because the Tessar design cannot be used as basis for large-aperture lenses, the Tessar was not the answer to the ambitious photographer’s wet dreams.

Therefore the history of the Tessar is divided into the pre-multicoating and post-multicoating era.

In the pre-multicoating era (before ≈1950), the Tessar was a high-end lens and was the go-to design when sharpness/image quality was sought and a higher price could be commanded. Some of the most desired after exemplars of classic TLRs (e.g. Rolleiflex) and folding cameras (e.g. Zeiss Ikonta) came with Tessar lenses (while the lower-end models used other, long forgotten designs).

The development of mainstream multicoating changed everything. Suddenly various Double-Gauss designs – that theretofore had been impractical due to the high element count and resulting flaring characteristics – became possible. Moreover, they offered the ability to construct standard lenses that let in four times more light than the brightest Tessars ever had. This instantly relegated the Tessars into the medium segment (they were still far easier and cheaper to produce than Double-Gauss lenses while still being less cheap than Triplets).

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 Tessar design.

Versions

There area lot of different versions of the Industar-50.
• First, there are versions for rangefinders (Leica Thread Mount) as well as SLRs (M42 and Zenit M39) with all the differences in flange focal distance that entails.
• Secondly, there are the retractable versions as well as the non-retractable versions.
• The Industar-50 has been offered both in silver and black.
• Through the years, a wide range of minor cosmetic/ergonomic tweaks have been made.

Adapting

This chapter will discuss adapting the Leica Thread mount version of the Industar-50 because it significantly more common than the M42 version. If your interest in adapting a M42 version, see the JAPB article on the M42 mount.

To use this lens natively, you will need a Leica thread mount film body. This means either a Leica body from before the 1954 introduction of the Leica M-mount, a Soviet Leica (Zorki or FED) or one of the more modern Japanese LTM rangefinders. You can also use this lens on any Leica M mount body using the LTM-Leica M adapter ring.

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, LTM lenses are so uncomplicated that a simple ‘dumb adapter’ will do the job perfectly. However, due to LTM mount’s relatively short flange focal distance, special adapters (helicoid adapters, tilt/shift adapters, speed boosters) are not an option.

Due to the short flange focal distance used by LTM cameras, there is no meaningful way to adapt this lens to any SLR or dSLR.

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. ↩︎