Separated Sonnar Repair

Discussion in 'Classic Manual Cameras' started by mskovacs, Jan 4, 2005.

  1. Well I'm really pleased with the outcome of this project. It started with my $25 ebay Carl Zeiss Sonnar 50/1.5 with separation and an idea I found on the net posted by Rick Oleson. Using the instructions on Mike Elek's Sonnar disassembly page and my new spanner wrench set, I got the lens apart. I spun down WD-40 in my lab centrifuge and decanted about 1 mL into a syringe with a thin 24 gauge needle. I *LIGHTLY* applied the oil with the syringe by generating tiny drops and touching them to the seam of the inner triplet with the separation (between the front two lenses). I doubt I used more than 50uL total, probably less. One must be careful not to generate a bubble so I went slow. Still, I managed one bubble but upon standing in my desk drawer for almost 4 weeks now, there is no sign of any separation, even when I inspect with a magnifying glass. It looks *PERFECT* IMO. I removed the old aperture ring damping grease and replaced it with a synthetic substitute. There was no oil on the blades so I proceeded to clean and reassemble the lens. As Rick Oleson said you have nothing to lose by trying and I may have dodged the $300 Focal Point wanted to repair this. I will continue to use it and post if there are any problems. Henry Scherer repairs separation for a lot less but he said that he cannot fix this type of edge separation. Here is the result - this particular lens has a large bubble in the rear element near the edge. I'm not going to worry about it.
    00Aez3-21208184.jpg
     
  2. [​IMG]
    Carl Zeiss Sonnar 50/1.5 - before the repair
    Now its onto the business of taking photos with it again! Zeiss Ikon acquisition syndrome has resulted in two recent Contax II purchases. The first (B series - 1936) is almost overhauled if anyone is interested in the details.
     
  3. Mike -- that unrepaired Sonnar looked pretty ugly. Nice work! I have a couple of Bessamatic lenses but haven't yet tackled them. I moved my workshop up to my office but haven't touched anything since before the holidays.

    When you finish the Contax II, I'd be interested in hearing about a comparison with the Kiev. I would think "touch and feel" should be very similar, if not identical.

    By the way, how long did it take for WD-40 to make its way between the lens surfaces?
     
  4. Looks nice, Mike! The one I had done to develop that method wasn't separated all the way around the edge like yours, it was only about half way around. I don't recall exactly how long I kept it afterwards, I know it was over a year and I never saw any sign of a problem returning. The one I did also was an f/2.0 rather than an f/1.5, but a late model lens as yours is.

    I have never seen this problem on a Jena lens, and I have a very nice all-chrome Opton-Sonnar f/1.5 that has no sign of separation - but it seems to have been pretty common in the later Carl Zeiss Sonnars from Oberkochen. Perhaps a new adhesive that didn't age well. The 1.5 Sonnar is one of my favorite lenses, I hope you are as pleased with yours.

    rick :)=
     
  5. OK I will post on the Contax II when its done. The biggest difference I saw was the quality of the main body casting. It was really rough on the Kiev. I went further with the Contax, getting the casting down to the point that only the self timer was left mounted. Also, the rangefinder cam looked like a cast piece on the Kiev 4A and was of much higher quality on the Contax II. (machined?)

    I'm also curious whether there will be any differences between the B and J series Contax II. I heard that the light seals (or baffling) was upgraded from the earlier models. Zeiss seemed to fool around with the serials too. The B (export model with scale in feet) has the serial on the rewind dial, the inside bottom and the back. The J has it on the shoe and back.

    The B came with an uncoated 50/1.5 (needs work for oil on blades) and the J with an uncoated 50/2 collapsible. The 50/1.5 appears to come apart the same way as a Jupiter 8 but I haven't yet seen my collapsible 50/2.
     
  6. WD-40 moved into the void within minutes but it took a few days for everything to fill in. After a week, I could still see something if I viewed from an extremely oblique angle. After 4 weeks, I could not see any defect viewing the free group under any type of lighting or angle.
     
  7. Also, I should clarify that I decanted the clear, lighter fraction of the WD-40 as Rick originally wrote. The heavier component that you absolutely do not want sinks to the bottom. It will also settle out on its own in a few days upon standing so you don't need to centrifuge it, although its much faster and probably a purer separation.
     
  8. Another possible approach. Bake the cemented group to re-flow the balsam.

    I have this incredibly butchered Leica Summar. (Not my fault!) The front group was about 40% separated, all from one side. Separation so bad that it generated a ghost image.

    I just put it in the toaster oven, and slowly raised the heat to 400F. I was trying to figure out if it is just cemented into the mount, or whether the brass is bent over the group. (It's apparently the latter!) But, the heat did make the balsam liquify, and it mostly re-cemented itself. I did pinch the elements a few times (with potholder) to push them tightly together.

    Yes, there are a couple of bubbles, and a small remaining separation along the edge. But now the lens doesn't generate ghost images, just one very low contrast image.

    So re-baking a balsam-cemented group may improve the cementing.
     
  9. Zeiss did not use Balsam cement in these late model Sonnars. Heating would probably make things worse since the cement would not liquify as the three types of glass differentially expanded.

    I did catch an earlier post about your Summar today from google while I was looking for information on its optical formula.
     
  10. Sure enough, this page on Henry W. Scherer's site indicates that this irridescent separation is of a lens cemented with an Epoxy cement, which cannot be dissolved.
     
  11. Focal Point does manage to get this epoxy apart though they probably have more specialized equipment than Henry Scherer. I've read that it takes 200 Celcius in a hot oil bath to get it apart. John at Focal Point told me that he has fixed many dozens of these, but the fact that its a triplet doubles the usual price since it doubles the work to recement it twice.

    Deep fried Zeiss glass :)
     
  12. you want fries with that?

    :)=
     
  13. SUPERSIZE ME!

    Anyone want to donate a separated Biogon? ;)
     
  14. By the way, using oil to "join" doublets is quite common among amateur telescope makers making refractor telescopes. It might be good to look at that literature and see what oils they use, they might be better behaved than the fraction of WD-40 that is being used. (WD-40 is mostly Kerosene.)
     
  15. Anyone thinking about trying this may want to read this first.

    http://tinyurl.com/2wy3u2

    http://www.zeisscamera.com/

    Feli
     
  16. Sorry, but this is just typical Henry Scherer marketing savvy. The lens is still going strong.
     
  17. Sorry, but it's not a good solution and you are wrong.

    I recently had some of my lenses serviced by a high-end technician in Hollywood, who works on movie lenses that cost thousands if not tens of thousands of dollars and he agreed that this is a very bad practice.

    Harry may wax rather romantically about his work, but he is a professional at what he does and has probably forgotten more about servicing gear than most people know.
     

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