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cleaning aperture blades on Zeiss Flektogon 2.8/20 MC ?
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PostPosted: Thu May 27, 2010 3:48 pm    Post subject: cleaning aperture blades on Zeiss Flektogon 2.8/20 MC ? Reply with quote

I just bought a beautiful Flektogon 2.8/20 marked just with "Aus Jena".

The aperture doesn't open properly, the blades stick. When I tap it gently the blades move closed at a high aperture.

Furthermore the aperture ring isn't aligned properly. It starts at F8 and goes a couple of clicks past F22.

I found some tips on disassembly but nothing on cleaning the blades and certainly not on the aperture ring.

Can somebody please shed light on how to get this right? I can fix anything as long as I know how. Especially the infinity focus is something I do not want to mess up.

If somebody can explain step by step for me how to get at the blades, I will make a detailed photo report on it for posting here.

Thanx.


PostPosted: Thu May 27, 2010 8:52 pm    Post subject: Reply with quote

Hi,

propellor wrote:
I just bought a beautiful Flektogon 2.8/20 marked just with "Aus Jena".


So you bought the export version of the lens ...

Did you look at http://www.pekericli.com/ ? He has some notes on fixing the Flek 20/2.8 ...

Hope this helps ...

Cheers


PostPosted: Thu May 27, 2010 10:18 pm    Post subject: Reply with quote

Thanks,

I did find this one but it only covers the rear lens element. I also need to know how to get the aperture out so I can clean it.


PostPosted: Sat May 29, 2010 2:27 am    Post subject: Reply with quote

This reply might be long as I will pass an email exchange I had with either someone from this forum OR from the Kiron Klub yahoo group.

My first attempt to clean oil from the aperture blades of a Rokkor 58mm 1.4 was so-so. I ended up breaking down the lens mount and removing the group of rear elements which got me to the back side of the aperture blades. I then proceeded to use a fast evaporating chemical called Napthalene and q-tips and it actually cleaned up the oil. I kept apply it with the q-tip and cycling the blades to pull the chem up into the aper-assy and then stopping down to expose it to air and evap the oil and wipe gently.

Someone read that I did it this way and the ole chap was very verbose in his reply. Very knowledgeable in the area. Here's what he said:

Quote:
Roy, forgive me but as a retired petroleum geochemist and a former phototopographic editor whose job it was to "look for things" your use of "naphthalene" to clean oil from a camera diaphragm struck me as a bit funny.

I avoid taking diaphragm assemblies apart and prefer to flush the oil away with a solvent as you tell in your Kiron Klub post. I use a medicine dropper or a hypodermic syringe to dribble Coleman brand camp stove fuel at an upper area of the assembly with a was of lens tissue to promptly absorb the washings. I have done this successfully with a glass element very close on the other side of the iris. I use Coleman fuel because lab testing I did years ago showed it to be almost pure n-heptane and more important it leaves no residue when it evaporates. The lens tissue is less likely to leave lint than a Q-tip. I am cautious about actuating the diaphragm while it is wet with solvent because something might break, like one of the studs on a blade.

On occasion I have found that solvent flushing cured a sluggish diaphragm even though no oil was showing on the blades. I think oil and dirt on the pivots out of sight was the problem.

I am leery of using WD-40 on lenses or cameras but your described limited use sounds OK. The stuff is a penetrant with a strong propensity to flow everywhere and that same characteristic makes it cling to surfaces and resist removal. On rare occasion I have used penetrating oil with a soak time of weeks to loosen a thread-locked front element of a lens. Of course this made a clean up job afterward, but in that case I had a fungus cleaning job anyway.

Any lubricant left in service must be something that stays put and does not migrate to glass or diaphragm. The product known as "Vaseline" certainly does NOT meet these criteria. It has a range of molecules from little ones to waxes. I am not acquainted with "clock grease" but the name suggests a highly refined material that may have that "stay put" character.

We who have not been given repair training by the camera/lens manufacturer must learn from each other and trial and error. Sometimes this is better than the training, and certainly may be more up-to-date.

Mel

http://en.wikipedia.org/wiki/Naphthalene


Quote:
Roy, naphthalene is a specific chemical compound that is a solid with high vapor pressure. Moth balls. naphtha is a rather non-specific term for a rather light (somewhat volatile) mixture of mostly hydrocarbons. Originally stuff called naphtha came from coal but now it comes from petroleum. When I was a kid Mother had a "coal oil" lantern which was used when the electricity failed, as it did during most thunderstorms. Neighbors who could not afford to have their house wired still used "coal oil" lanterns. However, by this time (about 1930) the fluid used in the lanterns no longer came from coal, it came from petroleum and was called Kerosene. When I worked in the Lube lab at a refinery we had a cut called "D1 naphtha" which we used for cleaning oil from our equipment.

Your mention of using fluorescent light sounds good. Despite the coating of fluorescent powder some of the UV light from the mercury vapor comes through to give some fluorescence to many compounds and make them more visible. Now I will be alert to pick up a UV light source if I can find one cheap enough for my retirement budget.

Years ago on canoe trips of 2 to 10 days with explorer scouts (14-17) we used coleman stoves for cooking. The scout office was not too happy with that, but only we adults did any cooking on the stoves. To keep the boys busy, always we had something to bake beside a fire with a reflector oven. You can even make pizza in a reflector oven. Bake the crust by itself first, than add toppings and heat it a bit more.

Those were good days. Good memories.

Oh, you asked about mixing lenses. Well, maybe.

For the most part, zoom lenses are made of several--often four--assemblies of one to several pieces of glass mounted in a metal frame--call this a module. The positioning of even one piece of glass, and especially several, can be very critical as to tilting and centering or even rotating. This is done in the factory with special equipment. I never take these apart. Apparently these assemblies are made under clean conditions and rarely is there any fungus inside them, only the outside needs cleaning. (A trace of fungus may appear at the edges supposedly growing on the mounting medium but growing slowly due to the lack of oxygen in the sealed unit.)

Next, these modules are assembled into or attached to the chassis of the lens commonly called the lens barrel and fitted to be moved about with rollers attached to the module and running in one or more rings with cam slots. All this part of the mechanism is made by machining metal castings or stampings and is done to tolerances determined by the design engineers.

These tolerances of different pieces can cancel to make a better lens or they can add up to make one not as good. It is expensive to test the assembly step by step and do a trial and error to find each module that meets specs, so I doubt if much of that is done. More likely occasionally a finished one is pulled from the assembly line and non-destructively checked to see if it is good enough. These may be the ones sent free to one of the photography magazines for testing.

Can you see where this is going? If you pull one of these modules from one lens and put it in another lens of the same make and model chances are you will get something equal, not much worse, or maybe even better than original, depending on how the tolerances add or cancel. This has been done.

A typical case is a bashed front element replaced with one from a lens with a broken mount. See picture. The front of this lens was undamaged. Maybe the lens was held as a handle and the camera used as a hammer. Thwarted a mugger maybe? Who knows?

When I take a lens apart, I scratch marks so I can put it back exactly as found even though the piece might go back just fine when rotated 180 degrees. I have no means to accurately test the difference, so I trust the factory assembly.


PostPosted: Sat May 29, 2010 5:34 am    Post subject: Reply with quote

be careful ...

since the aperture only starts at f:8 and the other problems, there is a good chance that the previous owner messed with it already (and apparently without success .


PostPosted: Sat May 29, 2010 7:37 am    Post subject: Reply with quote

hk300 wrote:
be careful ...

since the aperture only starts at f:8 and the other problems, there is a good chance that the previous owner messed with it already (and apparently without success .



+1 -- As hk300 mentioned -- blades are very fragile things!

I have sent an email to you..


tf


PostPosted: Sat May 29, 2010 8:26 am    Post subject: Reply with quote

Thanks guys for all the info. I knew it is a difficult job. I am glad I didn't start yet.



@ Trifox; received.


PostPosted: Sat May 29, 2010 9:02 am    Post subject: Reply with quote

Bart, I've had this lens apart three times now.

If the aperture ring is wrong and the blades are sticking then I'd put my money on incorrect reassembly when the mount end was last refixed. I bet the little plastic rocker isn't positioned properly. This is one of the easiest CZJ lens to reassemble, nothing falls out when you remove the mount, but you have to get all the parts positioned properly before you refit it, and have a little patience.

You mentioned infinity focus. If it is set correctly at the moment. the thing to watch is not to turn the filter ring in relation to the body. This is how infinity is set. The setting is secured with a clamping ring which can work loose. This thread has pics and instructions
http://forum.mflenses.com/czj-20-2-8-flektogon-dissected-t27106.html


PostPosted: Sat May 29, 2010 3:41 pm    Post subject: Reply with quote

This is the rear of the lens with the mount removed (thanks to Anu for the picture)

Lever A connects with the aperture dial on the mount and moves in a circular fashion around the rear element. The rocker B is spring loaded and is operated by the pin and the A-M switch in the mount. The blades are held open by a spring and close to the minimum setting (set by Lever A) when the rocker is pushed.


To test whether the blades are sticking, hold Lever A at its midpoint with finger and operate the rocker B. The blades should close and open normally. Often the problem of apparent sticking is because this mechanism has been assembled wrongly or it may need a touch of lubrication.

When reassembling, set the aperture dial on the mount to 2.8 and open lever A to the max point. Make sure the pin and the plastic rocker in the mount are set correctly and carefully mate the mount with both levers, A & B.


PostPosted: Mon May 31, 2010 5:54 pm    Post subject: Reply with quote

Wow guys, so much information. Thanks a million. I just returned from an extended weekend, so sorry for the late reply.

I guess this lens is worth getting right especially since it is the "Aus Jena" export version. You don't see these very often.

Anyway, Petergd, wahta you are saying makes a hell of a lot of sense. I checked and the aperture blades seem to be free of oil gunk. And it does look as if the ring is positioned wrongly.
As soon as I have the time and tranquility I will open this beauty up and see if I can set things right. But I won't do it if I have only 15 minutes free, I know frustration will get the better of my temperament and the flek will be a spec on he wall if I don't get it right the first time.

So bare with me and I will let you know how this turns out. Id like to try it anyway asap.........


PostPosted: Mon May 31, 2010 6:11 pm    Post subject: Reply with quote

I don't know if there is such a thing as the export version. This implies a different version was made for the home market. "Aus Jena" was used on lenses exported to the USA because of the USA court ruling. The lenses sold in Europe and everywhere else still had the old Carl Ziess Jena label.


PostPosted: Mon May 31, 2010 6:18 pm    Post subject: Reply with quote

peterqd wrote:
I don't know if there is such a thing as the export version. This implies a different version was made for the home market. "Aus Jena" was used on lenses exported to the USA because of the USA court ruling. The lenses sold in Europe and everywhere else still had the old Carl Ziess Jena label.


I should have said "export label". It still is a nice enough lens.


PostPosted: Tue Jun 01, 2010 2:31 pm    Post subject: Reply with quote

Well, I found the patience to work on the Flek. I opened the back and tried the lever A and B bit and you were absolutely right Peter, The blades work perfectly and are clean as a whistle. So it must have been a case of inaccurate assembly.

So I put it back together again as you said. That also worked, but upon turning the app. ring I felt something go wrong. So I tried again, same thing. The ring didn't sit correctly, just as before I started work on it.

I checked the pics of http://www.pekericli.com/ and saw that the little plastic thingy that is supposed to hold lever A sat crooked.

So I dismantled the back mount and of course some little things fell out; 2 small balls and a tiny spring. I gathered these sit underneath the crooked plastic thinghy to provide the clicks in the app. ring.

I immediately saw that the plastic thinghy was broken. It is held with 2 screws through holes in the plastic thinghy and one of these holes is gone. That made the plastic thinghy sit crooked and that is why lever A slips out of the plastic thinghy causing the fault.

So the problem is obvious and the solution equally easy; put in a new plastic thinghy.

But where do I get a new plastic thinghy. Any ideas guys? Does someone have one lying around or can anyone point me in the right direction?

The pics:



This looks good, no damage, no real dirt.




The mount in 2 pieces. On the left ring, on the top you can see the 2 screwholes for the plastic thinghy with a hole in the middle for the 2 balls and spring



The parts. The silver axle with the head is what goes through the mount



The plastic thinghy. The rim of the left hole is completely sheared off. You can see that the guide for lever A is also a little damaged.


This wouldn't have happened until the seventies where plastic made its entry into the world. In the old days this would probably be a cast part.


PostPosted: Tue Jun 01, 2010 6:17 pm    Post subject: Reply with quote

Maybe you can make a replacement out of small sheet of metal?


PostPosted: Tue Jun 01, 2010 6:58 pm    Post subject: Reply with quote

If I have to, I can make something. But I prefer original parts. There must be one out there somewhere. I'll find it.......