Another irregular production Sonnar

dexdog said:
That guy does amazing work. I bookmarked his site a few months ago. There is a 6cm Sonnar currently on eBay. It is different than others I have seen in that the aperture and focus directions are backwards.
www.ebay.com

Zeiss Sonnar 6cm F1.5 L-39 SM Unusual Rare Lens with Caps | eBay

I believe made in East Germany.
www.ebay.com
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It is not only that. This one is engraved Sonnar 6cm f/1,5 goes to f16 and to 0.9m MFD. If this is not only a showoff it could be a different Sonnar formula. On Facebook there is another Sonnar 6cm that has a similar "wrong" serial.

6cm1.jpeg6cm2.jpeg

picture from top: top left Sonnar, picture from side: bottom left Sonnar
 
I'd like to take a 6cm F1.5 apart, if one ever comes my way. I suspect the 6cm was easier to engrave than 5.8cm. My lens is engraved 5cm, but is clearly a 5.8cm focal length.
 
I tried out this method from Jim Kason to detect decentering.

Simple decentering test - the last word

I have a much better test than this one now. Here it is. I'm leaving this post up for historical reasons, but I strongly recommend that you use the new test. From the mailbag: I just found your blog and have been really enthralled by all the data you've got! I had a question I
blog.kasson.com blog.kasson.com

Well, I find it pretty difficult to see decentering and how strong the lens is affected with this method. But if you like nightmares then this seems to be the perfect method to roast your perfect lens to ashes. I tried it with a dozen of my lenses and it shows more then decentering of lenses. It shows you defects! It is like the flashlight test for lenses... 🙈

DSC04476.jpg

My perfect clean glass Jupiter 3+ shows hints of decentering (left white crescend).


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That is one of my bad East German post-war Sonnar 5cm f/1,5 T. I expected some decentering but it shows some spots that look like separation?

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My Nikkor 5cm f/1,4 looks like it is affected heavily by decentering. Pretty clean though.

And now lets come to the star of the compilation... or should I say MOON... the Sonnar 5,8cm f/1,5

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Looks like Apollo 11 has landed. What is this? Is this a case where some elements were not polished? Well, it looks not decentered at last. 😅

In comparison my bad Jupiter-3 from 1963.

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Decentered and scratched? It does not look as bad as the 5,8cm.
 
This kind of test where you basically shows grinding defects and similar such issues mercilessly. The same thing happens in the "bokeh balls" if your lens has a particularly large bubble or scratch it can show up there despite not affecting the overall image. Which is, crudely speaking what you do with this test.

However, this mainly tests the lens on-axis and I am not fully convinced that this test actually tests for de-centering. For example if the paint on the lens elements itself has flaked it could cause internal reflections that will look just like that (and will also not go around the entire circumference of the lens). Further, also looking very similar is harsh outlining of bokeh-rings is often caused by the designer choosing to over-correct for spherical aberration (at that distance!!) and not necessarily de-centering.

Which I believe is what you are seeing with your Nikkor. Try it. Use the Nikkor up close near its NFD. No glow!
Because the designers chose to aggressively correct for Spherical aberration at portrait distances. The price for that is paid at longer distances, so now try infinity - lots of glow!

This is not a new discovery by the way, Dante Stella wrote about it here:

One thing we absolutely however do see with this test, which I guess if the "Sturzvisier" theory is correct should not be surprising:
The overall grinding level of finish and consistency of finish has more variance to it. Which makes sense, since the bar for "good enough" for an optical sight is likely lower than that for a camera lens. So you will get (by happenstance) some good samples, perhaps even the odd amazing one, and of course a lot of samples that would have been either parted out or rejected if they had to meet the quality bar for a camera lens.
 
Here's the test I described earlier, these guys know what they are talking about and I find them to be trustworthy:

www.lensrentals.com

Testing for a Decentered Lens: an Old Technique Gets a Makeover

What is Decentering and What Does it Do? Strictly speaking, decentering would involve one or more of the lens elements being off of the central axis of the lens. This would prevent the curved surfaces of the lens from bending the light properly. In severe cases it could result in halos or...
www.lensrentals.com
 
TenEleven said:
Here's the test I described earlier, these guys know what they are talking about and I find them to be trustworthy:

www.lensrentals.com

Testing for a Decentered Lens: an Old Technique Gets a Makeover

What is Decentering and What Does it Do? Strictly speaking, decentering would involve one or more of the lens elements being off of the central axis of the lens. This would prevent the curved surfaces of the lens from bending the light properly. In severe cases it could result in halos or...
www.lensrentals.com
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Very nice!
 
TenEleven said:
One thing we absolutely however do see with this test, which I guess if the "Sturzvisier" theory is correct should not be surprising:
The overall grinding level of finish and consistency of finish has more variance to it. Which makes sense, since the bar for "good enough" for an optical sight is likely lower than that for a camera lens. So you will get (by happenstance) some good samples, perhaps even the odd amazing one, and of course a lot of samples that would have been either parted out or rejected if they had to meet the quality bar for a camera lens.
Click to expand...

That is called SABOTAGE! 🤣
 
S. H., the lens barrel and mount looks a little different than the others I have seen recently. Better quality finish at least. The name ring looks too bright and shiny, engraving on name ring looks almost like CNC work. Finally, the screw in the lens mount that drives the helical is odd in that is a round head instead of a flat head screw. That said, I think that the lens is a Stuvi variant with 6 slots on rear fixture.
 
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Yeah, I think dexdog is right. The screw is indeed strange. It's supposed to be a flat-head screw that is countersunk. Not a domed screw.
I suppose it has gotten replaced over the life of the lens, you can see in another photo of the listing that the screw doesn't quite fit right. And the focus scale ring is missing its screw. So there definitely was some attempted disassembly done here.

stuvi_side.jpg

Exempting the name ring which is indeed nicely done the fit and finish is similar to the one I have. Mine had a "T" engraved, which someone attempted to remove. Interestingly the removal of the "T" must have happened some time ago since the scratched brass is very oxidized.

Lastly the listing version has a sloped RF cam, which I presume is an earlier version of the lens.
The serial number, for what little that's worth, is also lower - 27.
 
I did a flashlight test with my Sonnar 5,8cm f/1,5. And it has some issues like a little bit of fungus. There is a little bit of fog inside the lens that could further decrease the contrast. The heavy structure you see in the bokeh ball sample of this lens comes from the rear element. While the other elements look polished this one has a rough surface to it that can be seen in the right angle of light. It seems it is the outside surface of the rear triplet that is affected this way. It very much reminds me of my v1 Sonnar 5cm f/2. This has a similar defect at the front lens. I have seen this with other v1 Sonnar 5cm f/2 lenses too. My Sonnar f2 has undergone a CLA but the front could not be fixed by cleaning. I imagine that a proper polishing could fix it. But I wanted to keep this Sonnar f2 in this state as it creates heavily vintage looking images. 😅

Lets wait if I give the 5,8cm a proper CLA with polishing. I will try to take some images to show this defect here. But not in the next days as my Lady wants to spend a nice time with me. 😄
 
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Another "stuvi" lens on ebay, you can see the the 6 slots in several pics of the rear of the lens on the auction site. This lens is marked 5cm, has a slope cut into the rangefinder cam, also has the "backward" aperture and focusing rings. How in the world does anyone crack a lens straight across the front element?

www.ebay.com

Rare Carlzeiss Sonnar 50 F1.5 Original Brass Ltm | eBay

Find many great new & used options and get the best deals for Rare Carlzeiss Sonnar 50 F1.5 Original Brass Ltm at the best online prices at eBay! Free shipping for many products!
www.ebay.com
 
I was intrigued by another odd "sonnar" on ebay, it was marked 6cm f1.5 and was unlike the several other examples I have seen recently. Has the typical 6 slots in the fixture around the rear group.


 
The lens mount has three has three small holes that I assumed held screws, but the holes are not tapped, are crudely drilled and not deburred, and are actually open all the way through to the helical (I can see helical threads looking through the largest of the three holes with a 10x magnifier). The rangefinder cam has a crudely filed slope to accomodate the 5.8cm apparent focal length. The aperture ring is held on by a single screw. The DOF scale on the mount was never engraved with the usual aperture numbers, although the lines are there.

 
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"Backwards" aperture and focus rings. The front of the optical fixture for front element is threaded (about 49mm) but someone has glued strips of felt around the perimeter, presumably to combat reflections from the shiny metal beneath (hard to see in these pics, and I am too lazy to find a macro lens). I will have to check if I have any 49mm filters on hand.

 
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Fortunately, the glass in the lens is in pretty good shape, unoated of course but minimal scratches or other damage. The lens will focus at infinity (about 300 meters) and close-up (about one meter) on my Sony a7iii. However, the sloped cam is not properly cut/filed as a measured 5 meter distance in my house shows up as 3.5 meters on a leica iif and canon P. The lens takes decent pics, point of focus is on columbine flowers (Aquilegia canadensis) about 2 meters away at f4
 
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I have not attempted to take the thing apart yet, although it is tempting. Lens mount has one big screw that holds it onto the helical, focus ring one tiny screw, no idea how the aperture ring is attached, it might have screws under the focus ring. The name ring as no spanner slots, so I speculate that the front element is permanently mounted in the front ring. Not feeling brave enough to disassemble yet. A weird lens all-around, and by far more crudely made than the other 2 "stuvis" I have.
 
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I have started to take the lens apart. The big screw that holds the lens mount onto the helical is attached to a small follower or shoe on the inside of the mount that tracks in the cut for the helical. It will be a challenge to get the follower back in place, I can see why other lenses just use a longer screw in place of the follower.

Machining of the helical is pretty nice, but the work to make the track for the follower looks like something I would do with a dremel after a few beers!
 
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I removed the screw from the focus ring and figured I could just unscrew it off the helical from the bottom, but that does not work, it gets stuck on something, although I cannot see any more screws that would trap it in place
Focus ring screwed as far forward as possible

Focus ring screwed as far back as possible to the point where it gets stuck. The proper position is somewhere in the middle
 
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There are three small screws holding the silver sleeve that acts as the rangefinder cam. This silver sleeve slides over the lens fixture with the 6 slots cut into the edge of the ring.


I was really surprised when I gently wedged the silver sleeve off.


I guess this is why a number of these "stuvi" type 5.8cm lenses have serial numbers that start with 1407. CZJ used a similar format for parts numbers or small items. Enough for today. I do not see any screws under the focus ring that might hold the aperture ring in place. I will ponder what to do next. Any advice from lens repair wizards would be appreciated.
 
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