With a flange back distance of 28.8mm, the M39 mount is one of the closest to the 18mm of the Sony E mount flange back. It allow to use a very thin adapter ring. Considering that I was expecting the Industar 50-2 Pancake to become a nice 50mm pancake for my Sony NEX in order to complement the Sony SEL 16mm.

Industar 50-2 pancake

Industar 50-2 pancake zm39

In fact, this model is not a real pancake when adapted to the Sony NEX. There is a trap:

If you have a look the the following list you will notice that the M39 mount adapter is very thin for the Sony NEX compared to all the others but the Leica M.

m39 to Sony E-mount adapter

m39 to Sony E-mount adapter

 

m39 to Sony E-mount adapter

m39 to Sony E-mount adapter

  • Leica M mount to Sony E mount adapter ring thickness: 9.8mm
  • M39 (LTM) to Sony E mount adapter ring thickness: 10.8mm
  • Konica AR to Sony E mount adapter ring thickness: 22.7mm
  • Canon FD to Sony E mount adapter ring thickness: 24mm
  • Minolta MD to Sony E mount adapter ring thickness: 25.5mm
  • M42 to Sony E mount adapter ring thickness: 27.46mm
  • Olympus OM to Sony E mount adapter ring thickness: 28mm

Any opportunity to adapt a compact M39 lens on the NEX would turn on a very compact combination. That was my expectation when purchasing this pancake.

m39 to Sony E-mount adapter and Industar 50-2 zm39

m39 to Sony E-mount adapter and Industar 50-2 zm39

Unfortunately this M39 pancake model of the Industar 50-2 correspond to the ZM39 mount. The real M39 is not a pancake. This model is the ZM39 version that was used with the 1955 Zenith C SLR camera. The lens flange to film plane register is different from the regular M39 mount even if the lensmount is a 39mm screw mount.

As a consequence it will not focus infinity when adapted with the regular M39 adapter ring.

(Even with the provided macro extension tube that is not long enough)

Industar 50 3.5 m39

Industar 50 3.5 m39

The built quality is really disappointing: the iris ring is click free but it is not very well assembled. It was made by the KMZ factory near Moscow in Russia.

Industar 50-2 zm39

Industar 50-2 zm39

It is a pity that this lens does not fit on the Sony NEX because it would have turned into a very compact combination:

It would have been very compact...if compatibles

It would have been very compact...if compatibles

Moreover, it’s optical performance is supposed to be good since it’s optical formula is the Zeiss Tessar one.

Will never focus...

Will never focus...

 

Definitively not campatibles

Definitively not campatibles

 

The real M39 50-2 Industar (dedicated to rangefinders) could have been an opportunity (or in M42 mount) but it’s size is not the same.

The only way to use this lens on a NEX would be with the following combination:

With a M42 to E mount adapter and a M39 to M42 reduction ring inside (since zm39 and M42 have the same flange back distance).

Considering that this is no more a pancake format, I went for the Konica Hexanon AR 40mm F1.8 with no regrets.

So when you plan to purchase a M39 lens, I recommend that you ensure first that it is not a ZM39 mount one!

That being said, I still consider that the M39 mount is interesting and I will try to adapt other M39 lenses soon…