Authentic Leica Mount 5cm F1.5 Sonnar, Disassembled

[Brian]

I was recently sent a CZJ 5cm F1.5 lens in Leica Thread Mount that was "underperforming". That means it would not drive the camera's RF to infinity, and yielded a badly-out-of-focus image. I was granted "full artistic license" to make something of it. There was some question as to it being an authentic wartime Sonnar, or a faked J-3. Well, I'm convinced that it is a real wartime Sonnar and am posting these images from taking the lens apart.

Everyone's familiar with the "little m" on the authentic lenses, and big "M" on the J-3... Including those who make counterfeits.

On this lens: note the two set screws on the focus collar. The lower one acts as a stop for the close-focus for the helical.

[Brian]

The helical is held into the lens mount by ONE little set screw! Unlike a J-3, you have to remove the helical from the mount to get the focus ring off. I call that a design flaw, and will explain later. Like when I put it back together, and tried to get the helical back into the mount and get the set screw back in with the focus ring sliding around... Point goes to J-3 design!

[Brian]

The Sonnar has a nicely stamped serial number for the rear module. The J-3 has it not-so-neatly scratched into place.

The "T" coated Sonnars have a set screw holding that read module in place. You must get it back into position EXACTLY or else the module will not screw back into place. The J-3 does not have this set screw.

You can see the location of th set screw near the small etched line on the rear module.

[Brian]

The Serial Number of the lens is etched into the inside rim of the helical, which you can find after unscrewing the optics module. Some J-3's have this as well.

[Brian]

The Helical has its own serial number nicely engraved into the components. And look at those Taps for the set screws. NICE. Points go to the Sonnar. I can't make taps that nice...

[Brian]

On this lens, "infinity" seemed to be at 20ft. That will not do. I found the helical was not properly screwed into the mount. I set the focus to Infinity, took a known-good camera outside, and screwed the helical in until the RF indicated good "Infinity" (okay- more like 600ft). And GUES WHAT! The Tap for the set screw lined up exactly! Well, at one point in time it went to infinity. That time has come again. Also- note the Line on the chrome trim for the Aperture index rather than the RED DOT of a J-3.

Oh. Forgot. Have to UNSCREW the Helical, and put the Focus Collar ON, and SCREW it back in and TRY to find that Set Screw Tap Again, and THEN get the set screw into the hole! Best Stupid Look wins out again! There just is not enough room to get the set screw into the hole with the focus collar in place UNLESS you turn the ring so that Infinity lines up with the set screw. THEN you get the slightest bit more of clearance to get the screw in... German OverEngineering...

[Brian]

After setting the Helical in place, the Focus Ring has to be repositioned so that the Distance Scale corresponds to reality. It moved, and I had to drill out new taps for the set screws. Not easy. The lens now has two set screws and one stud holding it in place.

This lens had one other hidden problem. I ended up collimating it only to have the focus drift off after a few minutes of use. Collimated it four times, and just about gave up. I thought the internal mechanism for the double helical might be off.

Then, I gave the lens a quick shake, and heard a "jiggle". the internal elements were loose just enough to knock the focus off. Took it apart, tightened up all the retaining rings for the optics, and collimated it properly. This time it held, and checked out at two set points with the RF. That typically means it is collimated, and the focal length is correct. If the elements are out, the focal length would have been off, and it would not have passed the two-point calibration test.

[Brian]

Footnote. Looks like this lens will be staying with me. I'll be shooting a test roll, and comparing it with the ones that I made. Shoot film- develop and .... scan. Simlar, wartime Sonnar, 1956 J-3, and a Contax II test.... the 1937 5cm/1.5 Sonnar did really well on the Leica CL. more scanning...

[jmkelly]

Agreed, Brian - this does not look like a faked lens. Heck, the serial number on the back of the optics matches the front ring. All brass? Thick shim though, like a J-3? Externally this lens looks much like the one you repaired for me (though mine has that unsuual "hand-machined" aluminum optical group). Stephan Vanden Zegel has posted some interesting pictures of similar lenses over at ZICG.

[Brian]

It's not brass like the earlier uncoated lenses. The alloy is high-quality, and matches that of the 267xxxx Contax "T" coated lens that I have. Note the chrome nose on this one, i've seen later wartime lenses with a black rim up front.

Do you have the link to the pictures at ZICG?

[jmkelly]

Stephan's original post at ZICG here (http://groups.yahoo.com/group/ZICG/message/10253). Pictures here (http://groups.yahoo.com/group/ZICG/photos/album/482081013/pic/list). Same pics on Sylvain Halgand's site, referenced in Stephan's ZIGC post, accessible to ZICG non-members here (http://www.collection-appareils.fr/phpBB3/viewtopic.php?f=6&t=3993).

[Brian]

I received the first roll back from the repaired 1941 Sonnar. I'm very happy with the results. Six hours well-spent bringing this lens back to operational use.

I spent last Friday at the Marine Museum at Quantico, Virginia. Of the various military Museums that I've visited, this one emphasizes the People and Events rather than the Technology. It is worth visiting.

All photo's were wide-open, EXCEPT the shots of the beach Landing. Those are at F4.

http://www.ziforums.com/album.php?albumid=90

and one photo, wide-open at about 1/15th second. This lifesize diarama was refrigerated and Dark, to give a sense of that night in Korea.

http://www.ziforums.com/picture.php?albumid=90&pictureid=727

[Amin Sabet]

Brian, that is a great album, and I especially like the photograph you've embedded in this thread. Not only does it look the most real, but the tight framing and cool background color make me feel cold looking at it.

[jmkelly]

Brian - that lens is the shizzle! You have ressurected a real winner here. The shot of the timeline is interesting - shows that while the Sonnar works so well on the "action" shots, I need to carry a Planar in my bag for flat subjects.

[Brian]

Thanks!

I'm so used to Sonnar's, Zeiss, J-3, Canon, Nikkor... I was thinking Wow- that 1941 image is really sharp across the field! I can read all the words! One of my optics books shows the field curvature for the Zeiss Sonnar as a function of distance from the center of the image. It looks like a dampened Sine wave.

[Brian]

Well, I'll be taking apart another one. Looks real in the photo's! We'll find out soon enough.

[Brian]

Okay! Lucky me. well, lucky me? Good thing I like taking things apart. and I got another wartime Sonnar last week, if it was in the war it served onboard ship at sea. My theory for all of the corrosion on the outer metal. It cleaned up fairly well, and I'll be testing soon. The hidden numbers were all present, and the helical was numbered "205". It's a later lens than this one, a "285xxxx". It had a rough life compared to this one, and I think the choice in metal suffered a bit as the war went on. BUT- the inner helical was just as nice, and cleaned up well after an alchohol bath. Pictures coming.

[dunk]

Very informative post ... Thank you. I've seen a similar lens for sale and am going to check to see if it has the small 'm'.

Cheers

dunk

[like2fiddle]

Really nice album Brian. The color rendered by these old sonnars is unlike any modern lens.