Carl Zeiss Jena Prototypes, Experimental, and Transition Lenses,

I recently acquired this 270* series wartime rigid Sonnar 5cm f2. Only the front element seems to be coated, at least the rear doublet isn't. Coating is not in the best shape and there is some haze inside the triplet group in front of the aperture that I cannot clean. It's between the glass elements.

The mount/outer barrel is interesting, it's heavy – definitely not aluminium – and uses some kind of thread adapter/step down ring to fit the optical block. I haven't seen this kind of late serial rigid 5cm before. I assume it's a lens block from a collapsible lens that was adapted into a rigid shell, possibly sourced from a soviet lens...?!

The main issue is that the lens won't mount. Not on my Contax iia, not on my various Amedeo adapters. The lens was definitely used, but I don't know how anyone would have mounted it. From what I can tell, the guiding rails of the mount are machined too thick. This would be difficult for me to file into shape, so the lens is basically a paper weight. Luckily it was only 65€.

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According to Thiele this should indeed be a Contax Sonnar out of a batch of 2000.
The batch and this lens was finished in late 1942. And I have seen plenty of lenses with spotty coating in that period. I guess supply constraints/labor shortages/etc. were a real issue.

I have had lenses where the "flag" part was a bit too wide and it would not mount on all cameras easily, but I never have seen such a lens where the mount is off entirely. It reminds me a bit of my "Zorky" branded Zonnar Kransogorsky which is also rigid and finished a bit crudely, but mounts. Maybe Brian knows something?

The mounting ring to make the lens into a "rigid" one has been made by Zeiss as early as the 1.4million Sonnars. The good news for you is that you can most likely re-use this mounting adapter ring to "rigidize" another f/2 collapsible Sonnar if you have a shell left over. Or give this one a new lease on life, I guess.
@lukx Interesting find. I have a similiar one right next to yours:

Ebay 2.709,855

It has the typical front of a collapsible f2 Sonnar of 1942 but the mount of a post war East German CZJ Sonnar. Indicator is the black arrow as aperture mark. Interestingly the lock pin is a red painted plate that was never used by CZJ on the complete silver mounted post-war Sonnars.

Looking closely at yours the mounting part seem to be donated from a Contax Jupiter-8. The red dot as aperture mark is an indicator as Zeiss never used red dots for Sonnar lenses.

Both lenses are no authentic Zeiss Sonnars. They where reassembled later with spare parts from other Sonnar / Jupiter lenses. Valid lenses from the same batch:
Here are 2 examples of those late term separation issues:

Ebay 1.888.701
Ken Rockwell 1.889.158

Yes, the cemented triplets where very expensive to make and slowly where superseded by other designs. But the show stopper was the rise of the SLR camera. SLR killed the RF concept. Not only Zeiss dropped the RF manufacturing. It was an international trend and the German industry was starting to trail the Japanese manufacturers here.

The Sonnar design is not usable on SLR cameras. The flange distance is to short for using it on an SLR. You can use it on a mirrorless though. But if you need a mirror you use a Planar design instead. And so with the rise of the SLR the Sonnar design was scrapped.
Wasn't the original 105mm f/2.5 Nikon SLR lens a Sonnar type? Maybe Sonnar derivative 50mm lenses won't work on SLRs, but I think telephoto variants can.
Wasn't the original 105mm f/2.5 Nikon SLR lens a Sonnar type? Maybe Sonnar derivative 50mm lenses won't work on SLRs, but I think telephoto variants can.

I have had moderate success with Jupiter 8's and the Bertele on an X2D. In my case it is not lens failure. ;o)

Wasn't the original 105mm f/2.5 Nikon SLR lens a Sonnar type? Maybe Sonnar derivative 50mm lenses won't work on SLRs, but I think telephoto variants can.
Yes- it is slightly revised from the Rangefinder 10.5cm F2.5, rear element moved closer to the aperture by 1mm- according to the Nikkor Nights story. In ~1971 or so, the 105/2.5 Planar formula lens replaced it.
Did someone investigate the origin of those LTM 5cm 1.5 Sonnar lenses with the aperture dot indicator? I'm talking about those LTM copies that look like a regular CZJ Sonnar but have a red dot as aperture mark. CZJ used a black line as aperture mark for their LTM 5cm 1.5 Sonnar.

Here is an example at Ebay.
Here is another example.

What strikes me is the quality of those non official Sonnar lenses. It almost looks like an authentic CZJ LTM Sonnar. Most of the time those lenses are in a very nice state with shining chrome body. But there are some interesting differences to the CZJ LTM Sonnar.
  • red dot as aperture mark (instead black line)
  • all number use a dot instead of a comma (,) for example 1.5 (instead 1,5)
The focus ring shows a small m letter so it is not a simple Russian copy. The name ring looks exactly like a valid CZJ Sonnar but a lot of times the serial number do not match with the production runs from Thiele Nummernbuch.

I would really want to know who build those Sonnar lenses. Are they 100% fake? Did this CZJ or some former CZJ employees?
I call these Transition lenses, Chris - owner of Skyllaney calls them Coburg lenses.

I believe these were made after the war, in Germany- using what was left after the war. They are irregular production. Often they lack the internal serial numbers of the focus mount. I've seen them without a distance scale. I have one that required the middle triplet be changed as the original was not finished- the front surface was not properly polished. Not counterfeit- the product of one-off manufacture and assembly.
What I call transition lenses- 2859291 does not have a Distance scale. Some were misassembled. One required the RF Cam to be polished down. The owner bought all of these pre-Ebay, I looked at them almost 20 years ago.
First set- from one of the "Irregular Sonnars.

This one is from a regular production, 272xxxx Sonnar.

This gives an idea of how many Wartime LTM Sonnars were actually manufactured.
I checked the serials... 3 of them found their way to Ebay in the last 2 years. :ROFLMAO:

2.858.462 is still online.

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As I suspect, this means one thing.

Jerry used to go to the camera shows. I've bought from him for over 40 years. At one show- asked me to look at these. I bartered for some LTM lenses that were good for parts, rather than accept money.

I tested all of the lenses, made four of the five focus properly at all distances. The odd-ball 255x has a focal length longer than 52.4mm, probably one of the 5.8cm F1.5 Sonnars in a one-off mount.

The one with no distance scale.

and the one with distance scale-

All needed work. Also had old marks from Fungus, which cleaned up well.
One of my conversions showed up on Ebay-

But makes me appreciate my collection of Sonnars even more.

This one is irregular production- notice the rear fixture, the retaining ring for the rear triplet has spanner slots. The fixture itself does not have spanner slots cut into it, as do regular production lenses. The finger grips on the aperture ring have too many grooves, and is wider than regular production lenses.
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To add to what Brian already covered, in my experience these irregular production lenses are originals - as in made from original parts that workers, post war, scavenged out of a bin of rejects or not yet assembled lenses.

Quality wise I can echo what Brian already said - some work right out of the box, some need work. The construction always has a one-off quality about it. Some are very shoddily put together, some others are exceptionally well made beating out even their regular production brothers.

In respect to their optical performance we have a similar picture (heh) - some of these lenses have a very sub-par performance, I have also had lenses that had the inner or rear triplet optically de-centered meaning that one side would come into focus sooner than the other. (I know this was an optical issue because re-mounting into a known-good shell and optical block did not resolve it.) some others however - are among the very very best Sonnars I own.

But unlike the regular production lenses, which are all at the very least "decent" when in working condition, what you get is a total gamble.
. . .

Jerry used to go to the camera shows. I've bought from him for over 40 years. At one show- asked me to look at these. I bartered for some LTM lenses that were good for parts, rather than accept money.

. . .

Small world. I often worked w/Jerry in our respective gov't day jobs before I really got into photography (around the time he was close to retirement).
Rauber, that is an odd one all right. The focus mount looks different than any other M39 Sonnar that I have seen,and the fact that it focuses "backward" makes it even more odd.. Makes me wonder if someone screwed a 272 Sonnar optical block into a custom/bespoke/one-off mount. Part of a batch of 3000 lenses made in 1943, in part M39
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I've seen several one-offs, Sonnar lenses in custom made focusing mounts.
I know some machine shops that make custom optical fixtures- used them for decades, would be able to produce the single-helical custom focus mounts like these.