Repairing Contax Zeiss 50mm f1.4 lens

[mtjade2007]

My Contax 50 mm f1.4 Zeiss lens has run into a problem of oily aperture blades. The blades eventually remain stuck on wide open now. I know the only way to fix it is to take it apart and clean up the mess on the blades.

I have repaired some Pentax lenses before. The first thing to do is always to unscrew the name ring around the front glass element on Pentax lenses. Once the name ring is unscrewed things are exposed and it becomes apparent what to unscrew next. I was able to repair an oily blades problem for a Pentax lens once.

Well, the Contax Zeiss lens is different. The name ring is not removable. Under a magnifier I can see that it is actually a part of the front barrel. So I guess the front barrel can be unscrewed off.

Does anyone ever repaire one and can confirm this? Or does anyone know the procedure of taking this lens apart for repairing/cleaning the aperture blades? I can't find any information about repairing Contax Zeiss lenses any where. This lens is one sharpest standard lens I ever owned. I am reluctant to give it up. Any information about repairing it is much appreciated.

 

[WRSchmalfuss]

Google is your friend, why don't you look at www.zeiss.de, or send them an e-mail!

Cheers

 

[ic-racer]

Around 2004 my Zeiss 60mm MakroPlanar (Rollei QBM) aperture blades assembly fell apart. I had Marflex in NJ repair it.

Its been a while, but to take apart the Rollei Zeiss 50mm 1.4 lenses, I take the bottom off first. The focus ring itself has a stop for infinity, but it connects to an underlying ring with 3 screws and that underlying ring has no stop. So by continual twisting of the underlying ring it allows you to unscrew the lens assembly all the way. There are two sets of helcoid threads (coarse and fine). The relationship of them is important when getting it back together correctly (could take some or lots of trial and error to get it right).

 

[Steve Smith]

could take some or lots of trial and error to get it right

In my case it's usually: Error, error, error, error, there it is...... no it's not, error, error, error, got it!



Steve.

 

[John Koehrer]

Take a look around the outside of the barrel for three set screws. If this lens has them, remove them & unscrew the entire front section.
Some of the Nikkors use this method where the filter thread, decorator ring are one piece.

 

[Arvee]

Hi,

I have been into my 1.7 lens and the one thing you want to be careful of if you have to go in from the rear of the lens is the tiny spring and almost invisible ball bearing that provides the detents for the aperture ring. I looked for almost an hour with a powerful magnet before I found it. It is also a bear to keep in place when reassembling it.

Underneath the rubber focusing ring are three cross head screws. I've not been in this end but I'll bet you have to remove the front cell by removing it from the helicoid focusing mechanism. The rubber ring is cemented on but you can work a jewelers screwdriver under an edge and then insert a toothpick to work it around the circumference without causing any damage.

HTH,

-Fred

 

[ic-racer]

Fred makes a good point that on the 1.8 lenses the screws are under the rubber and I think there are only 3, but on the 1.4 the screws are visible and there are four total. Three smaller ones, and a longer 'index-pin' screw.

Based on the price differential between a Contax 50mm lens and the same Rollei lens, I'd consider send that Contax lens out for service. I have five of the Rollei 50mm lenses and some were either free or $25 buck or so. So, no big deal to take them apart etc.

 

[mtjade2007]

I have looked into the rubber ring. I removed it. There are no screws underneath it. The rubber ring is on the focus ring. The focus ring is turnable. The front barrel is not turnable. So the front barrel is really not attached on the focus ring. There are no holes on the focus ring underneath the rubber ring. So it is most likely the front barrel can be unscrewed off. Or it can be approached from the rear. I have tried to remove as many removable parts from the rear already. I can't find anything that may provide access to remove the front barrel.

I believe to access the aperture assembly the front barrel and front glasses (as a unit) need to be removed. The ket is to find out how to remove (unscrew) the front barrel. I worked on a Pentax 67 90mm Leaf shutter lens once. I could unscrew the name ring. After that it was obvious to unscrew 3 more screws and the front glasses in one module could be taken out. The shutter and aperture assemblies were down there visible and serviceable. For that lens I stop at there to blow off some internal dusts only. I reassembled everything back together. There was no optical alignment or anything like that involved. It was very easy to do.

I imagine if I can unscrew the front barrel of my Contax 50 mm f1.4 I will be able to attack the aperture assembly. Maybe I am too optimistic about it. I would like to find out if it is possible to do by myself based on my limited experience repairing a couple of Pentax lenses. But so far this Contax lens seems to be very difficult to attack. Thanks for your input, Ice-racer and everyone else. I will look again from the rear to see if this lens is similar to your Rollei lenses. I am willing to purchase a beat-up broken Contax lens just for the purpose of research. I talked to a couple of camera repair shops. They all couldn't tell me if they ever worked on one such Contax lens. I am reluctant to send it to anyone who has not repaired one. If they have to experiment to figure out how to take it apart chance will be high that the lens gets damaged.

I am hoping someone who has actually done it to tell me how it can be done. If I am not capable of doing it myself I will have to send it out naturally. Thanks a lot folks.

 

[Arvee]

I acquired the parts I needed for my 1.7 Planar from ToCad America Inc. They have a website and they were quite helpful in assisting me. This was several years ago but it might be worth a phone call to talk to a tech.

-Fred

 

[mtjade2007]

Thanks, Fred, for the great tip about ToCad. It looks like they still provide repair service for the lens. I will call them up and see if I can afford to send the lens in.

 

[ic-racer]

I have another Rollei 1.8 50mm in front of me. If I unscrew the whole front of the lens, it comes off and then 3 screws are visible, around the perimeter of the lens. Try unscrewing the whole front.

I had always thought the Contax and Rollei lenses just different in the mount, but perhaps the they are only the SAME in the optics and the style of the rubber rings. I saw a Contax 1.4 image on the net and sure enough, it does not have the screws on the focusing ring that are clearly visible on the Rollei version.

 

[mtjade2007]

Ice-racer, you are probably right. Contax 50mm 1.4 lens probably has the same design that the front barrel can be unscrewed off. I have tried to unscrew it but never made it so far. The problem is in tools. With bare hands it won't turn at all. The space on the front barrel is no wider than 5 mm. My hand simply could not have enough friction to turn it. I can not find a proper tool to try it. I actually bought a Micro-tools lens wrench. I bought the largest one they had. It is still not large enough. It is a 55 mm lens wrench. It needs to be something like 60 mm. I may need to build one myself. I am thinking of building one with hard wood. Any suggestions on this?

 

[ic-racer]

Have you tried a rubber 'jar opener' ?

 

[John Koehrer]

Set the lens to it's closest focus. This will give you a little bit more surface to grab. Check again for set screws that may have been hidden when the lens was at infinity.