Lens Mounts: Z39 (Zenit M39)

Pekka Buttler (1/2026)

This article is on the lens mount used by early Zenit Soviet SLRs which combines the 39 mm thread of the Leica thread mount with a decidedly non-LTM flange focal distance. This mount does not have a well-established name, but JAPB calls it the Z39 mount (short for Zenit M39).

In the early 1950s KMZ (Krasnogorski Mekhanicheskii Zavod) started design and development work on an SLR camera body. As basis for this development project, KMZ used the Zorki¹ rangefinder camera² (that KMZ also manufactured). That camera became the 1952³ Zenit SLR (nowadays often referred to as the Zenit 1) and it would turn out to be only the first Zenit in a line of cameras that would outlast the Soviet Union itself.

Image courtesy of Pete from Leeds, UK, CC BY 2.0 via Wikimedia Commons

Likely to avoid unnecessary retooling, the Zenit reused the mount mechanics of the Zorki, although the flange focal distance obviously had to be increased to make way for the mirror box resulting in the unique flange focal distance of 45,2 mm. The first Zenit was followed by a line of successor models (Zenit C, Zenit 3, Zenit 3M and Kristall) all using the same Z39 lens mount.

In 1965 KMZ introduced the Zenit E. That model changed from the Z39 mount to the ‘standard’ M42 mount. For some time KMZ manufactured the new Zenit E and the old Zenit 3M side by side, but in 1970 the manufacture of the 3M (and thereby Z39 mount Zenits) ended with comfortably over a million Z39 mount Zenits having been manufactured.

Z39 lenses?

Yes, off course. In the 50s and 60s the Zenit was the Soviet Union’s premier SLR and because no one else used the Z39 mount, the Soviet photo industry also had to supply all the lenses to be used with all the Million+ Z39 Zenit cameras. This also means that – at least until 1965 – Z39 was THE mount Soviet SLR lenses were supplied with.

From today’s perspective this means that many of the classic Soviet lenses can be procured more easily in Z39 mount versions, and that especially older samples are primarily available in Z39 mount.

Adapting Z39 lenses:

First off, all Z39 lenses have aperture rings and focus rings and do not use any type of camera-lens communication. This is good news, because it typically makes adapting lenses easier and that it is possible to manufacture a custom adapter from the Z39 mount to any other lens mount that has a shorter FFD. Assuming that Gyro Gearloose is not your alter ego, you will be interested in knowing how best to adapt your Z39 lenses using off-the shelf parts.

Adapting to mirrorless

If your intention is to use your Z39 lens on a mirrorless camera, that has a flange focal distance shorter that the 28,8 mm of the Leica thread mount, the optimal adapting solution for Z39 lenses is to get a 16,4 mm long LTM extension tube and put that between your Z39 lens and your LTM to <your mount> adapter. LTM to mirrorless adapters are available for all mirrorless systems up to digital medium format systems like the Hasselblad X and Fujifilm G systems. 16,4 mm LTM mount extension tubes can easily be sourced from eBay, because these were manufactured in their millions in the Soviet era (pretty much every LTM extension tube set manufactured in the Soviet union contained one 16,4 mm extension tube.

That 16,4 mm extension tube when coupled with any LTM adapter is a perfect match for the Z39 mount’s flange focal distance.

When coupled with an AF-adapter (and an LTM to Leica M ring), even autofocus becomes possible)

Adapting to SLR/dSLR

Alternatively, if you want to adapt your Z39 lens to use it on a SLR/dSLR, that too is possible but not entirely problem free. There are some DIY Z39 to Canon EF adapters that give you the correct flange focal distance, but if you want to work with off-the-shelf parts, you will have to use a M39–>M42 thread adaptor, and then treat the lens as if it was a M42 lens. However, because the FFD of the Z39 mount is 0,26 mm shorter than that of the M42 mount, you will technically not quite reach infinity. However with most lenses this difference is so minor that you might be able to live with it.

Footnotes

1. In true Soviet style, the Zorki was KMZ’s copy of the FED which in turn was a copy of the Leica II. ↩︎
2. Incidentally, the approach of remaking a successful rangefinder into an SLR was followed by Nikon when they in 1959 made their successful Nikon S series rangefinder into the Nikon F SLR. ↩︎
3. Yes, the Zenit 1 was introduce in the same year as the more famous Asahiflex. ↩︎