RZ67 lens disassembly

Discussion in 'Medium Format Cameras and Accessories' started by thisismyname09, Oct 30, 2009.

  1. thisismyname09

    thisismyname09 Member

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    I just got a 150mm lens for my newly acquired RZ67 body. It's in perfect condition, aside from the ridiculous amount of dust between the lens elements (which is why I got such a good deal on it...). So I figured, I'll just take it apart and blow the dust out. Easier said than done, it seems. I've got a 90mm K/L and had a 127mm K/L for the RB67, which are essentially the same lenses as the Sekor-Z, and I was easily able to disassemble those. I've got a spanner wrench that easily unscrewed the rear element on the 90mm K/L, but it won't move on the RZ lens, even when I used a terrifyingly dangerous amount of force extremely close to perfect glass. I'm stumped as to how to remove the front element, as well. Am I missing something here? Are the threads on the RZ lenses perhaps reversed just to mess with me? Does anyone have a copy of the lens repair manual they're willing to share?
     
  2. MikeSeb

    MikeSeb Member

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    Do you have a dust-free positive-pressure clean room in your home? Then are you sure you won't make things worse by trying to fix what ain't broke?

    Are we talking Tut's-tomb dust levels here?What image problems is this dust causing?

    This to me falls under the leave-well-enough-alone category.
     
  3. Q.G.

    Q.G. Inactive

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    Sorry, but i have no idea how to get into these lenses.

    But on the "positive-pressure clean room" thingy, which ranks very high on the exaggeration scale:
    If you're able to get the dust of your front lens without a clean room environment, you'll also be able to get the dust of any other lens surface as well.

    When you can figure out how to get inside the lens, go for it.
     
  4. Steve Smith

    Steve Smith Member

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    We have them at work but I have never thought about doing lens repairs in there.


    Steve.
     
  5. thisismyname09

    thisismyname09 Member

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    It's certainly not a "tut's tomb" level of dust, but its enough to the point that I can see a difference in the viewfinder compared to the 90mm K/L I have. The inside is noticeably much dustier than the front and rear elements after blowing the dust off with a can of compressed air.

    If nobody here can tell me how to crack the thing open, I'll probably have to blow $20 on a copy of the repair manual on ebay. The thing that concerns me, though, is that the only lens repair manual I found lists all but a few of the lenses. One of those not included is this 150mm.
     
  6. paul ron

    paul ron Member

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    Take the rear cell out of the back, it unscrews like a light bulb in one piece. That inside surface of the rear cell can be cleaned with denatured alcohol n a good cleaning cloth, not paper. Now you will have access through the shutter to the back surface of the front cell. Try blowing it out with caned air, don't use liquid cleaners here since this will just make the situation worse if it gets into the shutter n iris.

    If you have a floating lens and it has dust in the front part of the cell, leave it alone, it will require a pro to do this work. Opening this is asking for trouble.

    You don't need a clean room to clean a lens. You need clean hands, a good work place with good light and proper tools.

    .
     
  7. thisismyname09

    thisismyname09 Member

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    What exactly are the proper tools? I've got a spanner wrench that seemed to work with my K/L lenses, but the RZ lens I've got is impossible to unscrew. Is there a better tool for this job?
     
  8. nick mulder

    nick mulder Subscriber

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    I know at least the RZ back use reverse threads on some parts just to make home fiddling that much more of a head scratcher ...
     
  9. John Koehrer

    John Koehrer Subscriber

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    Re:front element Remove the decorator ring with a rubber stopper & access the spanner rings.
    Take a rubber stopper with the edge held at an angle, & rotate anti-clockwise.
     
  10. thisismyname09

    thisismyname09 Member

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    I was able to get the front off, but not the back. Is denatured alcohol the same thing as isopropyl alcohol or some other substance, or will I have to go to the store and find a bottle labeled "denatured alcohol"?
     
  11. thisismyname09

    thisismyname09 Member

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    A quick google search answered my first question, obviously I shouldn't be using isopropyl alcohol, but since denatured alcohol is mostly just ethanol, can I just use extremely strong drinking alcohol, like vodka or something?
     
  12. Rudeofus

    Rudeofus Subscriber

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    Vodka contains between 38 and 50% alcohol, the rest is (ideally) water. Denaturated alcohol is almost 100% pure, except for some intentional contaminants which make it unsuitable for drinking but in turn exempt from alcohol tax. These contaminants have very similar physical properties to ethanol, so tax evaders can't filter them out and the whole liquid works as residue free cleaning agent as intended.

    All said and done, your question boils down to whether 50-65% water content of vodka can harm the lens. I doubt it but would leave the answer to experts. Chances are that denatured alcohol is easy to get in any pharmacy and much cheaper than vodka, so why not just use it?
     
  13. polyglot

    polyglot Member

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    In AU, you buy "methylated spirits" which is ethanol and a couple of percent methanol mixed in to make it toxic and avoid taxation issues by making it undrinkable.

    I use isopropanol for all my cleaning purposes though.
     
  14. tkamiya

    tkamiya Member

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    Be careful with denatured alcohol! The denaturing material to make it non-drinkable, thus not subject to taxation, can be anything including gasoline and manufacturers don't always tell you exactly what they are. It can leave some nasty residue that is very difficult to get rid of. At minimum, I would suggest testing it on something other than your expensive lens. Personally, I would not use it on optical lens.
     
  15. paul ron

    paul ron Member

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    Not knowing which 150mm lens you have, not all are created equally. Some have screws under the rubbler finger grip strip on the sides, some have screws hidden under the thumb grips that get removed n access holes to the screws, the soft focus lens the entire front comes off to install disks n the access to the front cell is simple, floating lens style lenses need to disengage the floater lever n that will require realignment when assembling it again as well as clenaing all the elements inside the floater cell n relubing the helical, some lenses require removal of the name ring on the front n unscrewing the front cell like a light bulb. If you've seen enough of these lenses, you'd know by sight exacly how it opens.

    Denatured methanol alcohol is the same stuff used to make shelac, sold in paint stores. There are other names for it in other countries, but here in the US, it is called Denatured Alcohol. Isoprople will do just as well AKA gas line anitfreeze. Denatuered means it contains certain other chemicals that are just as volitile as alcohol to make it undrinkable. the chemicals don't leave any residue since they evaporate just as fast if not faster than alcohol. Wearing gloves is recomended, it is toxic stuff and is systemically absorbed and will defat the skin which can cause long term damage. Good air circulation is also recomended regardless of which alcohol you choose you use. Vodka is not good and will leave a residue, it will only make your job miserable unless you are drinking it, then you won't care what the lens looks like in the end. Rubbing alcohol will leave a residue. Watch out when cleaning lenses that have edge blackening... it will disolve the paint and will have to be reblackened. None of the alcohols will harm coatings... an urban myth.

    As for tools needed for lens work... only quality tools. Good set of screwdrivers is formost, good spaner n some mechanical intuitiveness. I made my spanners individually to fit the specific lenses I am working on instead of using an adjustable generic spanner. Rubber plugs, rubber straps, belt clamps, lens vice, 3rd hand, thread chasers n taps, micro drills, a few types of dental picks, hemostats, forcepts, scalple, q-tips, suction cups, screw organizers, a good loupe. Most important, a clean soft work surface n good light. Oh and having some great music going in the background so you completely forget what time it is.
     
  16. Alexander Ghaffari

    Alexander Ghaffari Member

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    *cringes* I've disassembled and reassembled 75 year old Zeiss lenses, with great success...but I wouldn't touch a much newer (and more complicated) lens, just for dust; however, that's just me, even though I am quite handy, regarding electronics and simple optics. Best of luck to you.
     
  17. thisismyname09

    thisismyname09 Member

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    I finally got the rear element out last night. As it turns out, the "dust" I was seeing is between two glued pieces of glass. It's a slight yellow tint and, obviously, looks like dust particles. Is this an early sign of fungus or lens separation, or something else I'm unaware of?
     
  18. polyglot

    polyglot Member

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    Could be separation but it's hard to say without seeing it. Can you focus a macro lens on the dusty/bubbly layer and post a shot of it?
     
  19. thisismyname09

    thisismyname09 Member

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    I don't own a digital camera, actually, so I can't post a picture. :|
     
  20. paul ron

    paul ron Member

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    Which lens are we looking at?
     
  21. thisismyname09

    thisismyname09 Member

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    The rear doublet on a Sekor-Z 150mm W.
     
  22. roger-wilco-66

    roger-wilco-66 Member

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    Just for the search engine, because there is already some good information in this thread.

    I took a 110mm Sekor Z lens apart because it had some tiny fungus in between the last element (facing the camera). The fungus sat at the edge of the outer lens and it came off without a trace. I managed to take all elements out and cleaned them, because there also was some dust and a small hair visible. Some noticeable things to mention:

    - the the ring that secures the last lens of the back element didn't come off. I removed the other lens (that ring came of easily) and put the element in a warm water bath, about body temperature. After waiting 10 minutes to let it warm up I tried again and it came off without an effort!

    - I cleaned the lenses in a bath with a drip of dish washing solution and destilled water, in a ultrasonic cleaner. After that I flushed them with destilled water and dried them with a fine microsynthetic tissue. They came out flawless!

    - I had some problems with the front ring - I don't have a rubber piece that fits in the conical shape of the ring. So I took a spray can that fitted right in the middle of the conus and a thick rubber glove, which I flexed around the can bottom with the flat back side of the glove. Hope you get the picture. The ring came out without effort turning anti clock wise.

    All in all it was a great succes and I have a "new" 110mm lens now :smile:


    Cheers,
    Mark
     
    Last edited by a moderator: Sep 23, 2015