Cleansing a 50mm Summar

Discussion in 'Leica and Rangefinders' started by www.flickr.com/photos/tmccabe, Feb 17, 2009.

  1. Hello there,
    I have a leitz 50mm F/2 Summar that I would like to take apart and clean. There are some huge chunks/haze in there and would love to get it out. I'm not worried about damaging it as it only cost me 40 dollars and I don't mind the haze, but that debris has to go.
    Is it possible to dismantle from the front? I'm aware of the aperture blades all coming apart. Screws are stripped badly in the back, so I won't be able to take it apart from there.
    Also any good solutions for taking care of fungus? I read somewhere soaking the elements in vinegar overnight? But I could be horrendously wrong. Thanks for your time.
     
  2. I can't help you with the disassembly of your lens, but this article may be helpful as far as treating the individual elements after removal.
     
  3. The front group is trivial. Unscrews. The set-screw in the trim ring unlocks the threads to separate the front element from the inner group.
    The rear group is a pain in the butt. Remove the bayonet ring by removing set-screws and unscrewing it. Don't pull the tube out of the focusing mount, you may mess up the felt. Loosen the screw on the side of the barrel. Now, make a custom ring wrench that's a strong snug fit on that last 1/8" of the barrel that is a separate part. Make a scribe mark to show the alignment of the rear cell with the lens barrel. Apply ring wrench, the rear group is a very tight friction fit.
    It is not essential to remove the rear bayonet ring. But it will be more challenging to make a tight ring wrench that can get around it. But you must remove the set-screw on the side of the barrel.
    There is a small screw ring on the rear group that you can remove to get out the rear element, using a spanner wrench. That is the only element that isn't "peened" into it's mount. All the rest require lathe work to get them out of the metal. (Meaning, don't try.)
    You need to replace the black paint on both the inner groups that face the diaphragm. I used Kodak Black Brushing Lacquer, which is long since discontinued. You want some sort of matt black lacquer.
    I don't think it's practical to clean off and replace the paint on the edge of the rear group through the front of the lens. The stationary ring of the diaphragm will be very much in the way.
    Your goal is to make the view through the lens "water clear".
     
  4. For fungus, the US Military repair manual for the Leica M2 and lenses calls for 10 parts of a 3% hydrogen peroxide solution with 3 parts 28% ammonia solution. Rinse with distilled water. If that doesn't work, try 180 proof ethyl alcohol.
    If the lens is coated, realize that the lens coating is probably so soft it will come off with a wet tissue. But most Summars aren't coated.
     
  5. John is giving you the correct info. If you don't repaint it inside, the old paint will just keep flaking off and you'll continually need to open it up (don't ask me how I know). I didn't find the rear element that difficult to open, but make sure you have good screwdrivers, not those cheap ones. Put everything on a white piece of cloth when you take it apart. I used a pair of needle nose pliers to spin off the grooved retainer, but you have to be careful it doesn't slip. Put LOTS of layers of tape on the glass just in case. The aperture assy on the front looked fragile so I never fooled w/ that. I cleaned mine so often I could do it in my sleep. It was the first lens I ever opened up other than an Argus 50 lens. Pond's Cold Creme is supposed to be the thing for fungus removal. Never tried it but a lot of people swear by it.
     

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