Contax I ribbons

Erik, prior poster Dralowid has provided drawings, primarily of the wind knob and what I call the winding room of the camera which not only provide detail that should go into a book (which I would be happy to provide (C) assistance) but for now, an additional poster enlightens that from the drawing it could be discerned that there is a small metal post controlled by a spring and adjuster to manipulate the shutter curtain travel width. Since the "sports" group speeds work independent of the slow speed escapements it may be possible to adjust the 0.65 mm 1/1000 width ~ now providing ~1/650 to a width much narrower, relatively speaking. Possibly, adjusting the timing of the second curtain release is the only problem and it is not clear from the post about the steel pin adjustability what it adjusts. My slow speeds do not seem to be too far off and are all consistent. If I could narrow the cathode ray TV elongated rectangele image by half i think I would be back to 1/1000. My understanding is that this adjustment is by way of the winding knob access so would not involve taking off the metal cover for the film platform. The camera is robust compared to the Contax II but for the small screws holding the film tensioners in the camera compartment, delicate, easily cross threaded if not careful.
When I find out what I can do about the width of the curtains adjustability I will post as I also have a fully working "f" model with film in it. Seeing how close the curtain was to my Nikon at 1/1000 on the cathode ray tube TV and that the image was not curved at the top or bottom really picked my interest in these cameras. Even my Pentax SP does not display an image form at 1/1000 not showing some type of undesirable acceleration. Of late I have had some time, as an aside, I notice what is being sold on Eday in the Canon variety and what is not working. I have an L1 which gave me slow speed nightmares...nothing I could do to make operate consistently....until...until I took prior camera expert repairer light shieling goo off the camera shell. That allowed shell to be positioned snug against the camera "main frame" but also the rod the slow speed knob group adjusts! So, for all RFF members who have shelved their L1 for slow speeds shoul know what may be done easily to uses camera again....very nicely engineered and sounding operating Contax I. Have to go to USPS...notified have Opton Sonar red T 50/1.5 in locker....a little fungus but what a nice lens!
Whatever you do, enjoy the day!
Tom S.
I complained about the "robustness" regarding film tensioners of I but II have same just not needed to remove on II to access the shutter compartment.
Persistence sometimes pays. Trying to figure out what to do about the "sports" speeds I noticed that 1/1000 setting was a little inside the gap for 1/1000 and 1/500 to get the pin to set right. So I tried setting the knob just counter clockwise, just counter clockwise to where the pin set on my operating normally "f" model Contax I. Not setting the pin, with it just a hair counter clockwise to 1/1000 and the image on my cathode ray tube TV showed an image matching 1/1000 in width. I have noticed that the further away from 1/1000, it seems the further away from where the pin sets I get where it should set. So, how can I adjust where the pin sets counter clockwise from where it now sets for the "sports" speeds. I will try this with the rest. Everything else is sounding right and the shutter seems to be operating in a full open to close manner.
Another look at what the drawing shows that Drawlowid posted. It may be that I totally have missed more in the prior posts...someone saying something like there was and infinite number of speed settings if the pin was not able to be set? Kind of like some of the Barnack Leica slow speeds set on the separate knob on the front....a continuous ability to set speeds between the detents. Yipee! Something to get closer to what I want before closing this "e" model up.
Yesterday I checked so me old messages and found that Dralowid had messaged me that he had parted with his Contax I, years old message so I apologize for going on with any requests or suggestions asking of any help there. This is not the first time I have posted to way old posts on a subject. However should anyone need help and anything I have contributed provide a way to an operating Contax I my time will have been well used. Often it is remote information that just may be of help. I recently bought on an auction site a Contax IIIa which arrived with high speeds all bad but a day or so I say a post that when all the high speeds are bad that is usually a sign that the works need cleaning and lubrication....well I tried a conservative amount of oil and jet fuel and the shutter perked to life, like new...for how long I do not know but the idea of having to open up the camera and tweak the spring tension of something of that nature evaporated! TYG
Tom, I hope this picture wil encourage you to carry on with your work on Contax I cameras. Somehow these cameras deserve to work in my opinion. They are the forerunners of the great Contax II and Kiev cameras. Without the Contax I these wouldn't exist.

gelatine silver print (nikkor 50mm f2) contax I v3.


I too have one that caps with speeds in the high speed groups (1/500th and faster), Up to 1/200th the exposures seem okay.

They can still be fine performers without the high speeds

Contax I (v5), 50mm f/2.5 Tessar, Agfa APX 100
After 17 Pages of Posts - what is the Best Contax I ribbon material ?

After 17 Pages of Posts - what is the Best Contax I ribbon material ?

title says it all.

I only have 6 Contax 1 shutters to repair.

As the originator of this thread and now thankfully devoid of all Contaxes I look down at the posts with an Olympian view and a certain fondness for these lovely cameras.
As the originator of this thread and now thankfully devoid of all Contaxes I look down at the posts with an Olympian view and a certain fondness for these lovely cameras.

Is that something like the statement "A boat owners second best day in life is the day he bought his boat. A boat owners best day in life is the day he sold it"?
Silk is the best material. It has no elasticy. Any elasticy of the straps is killing for this kind of shutters.

The greatest of all silk shutters is made by Nikon in the Nikon S2. There is no rubber on it, like on the Leica shutters, yet it is fully light tight. A miracle!

Well here goes to resurrecting a five year old post!

Wanted to report another "successful" Contax I (Version 6 - Y serial number) CLA thanks to the myriad of fantastic information for those of you that came before me.

As Nicholas knows I am not new to Contax camera repair but the Contax I sat on my shelves for over five years before I gathered the courage to dig in. It sort of worked, but the wind knob was extremely stiff and the lens mount equally so. Once inside I did find newer black ribbons in good condition so I let those be.

The results of my "CLA" are consistent with a camera made in 1931.... the speeds for the lower 3 groups are surprisingly accurate, while the "sports group" is consistently 1 stop slow with a shading 1/1000....

My question is this: When I actuate the shutter in the sports group I still hear the "Contax Weaze" something that does not happen in the Contax II where the high speeds are just accompanied by a nice "thud", does the Contax I shutter work differently here or is something not disengaging properly?



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My only working Contax I does "thud" with all the speeds in the sports group. I am not sure, but it is very likely that my working Contax I has Contax II shutter springs. I have three not working Contax I cameras. If you want to have a working Contax I replace the Contax I shutter springs with Contax II shutter springs.

Thanks Eric, something probably wrong with my group speed selector and something not disengaging due to gummy gears…. Will try some further cleaning of the advance / speed selector dial.

Beware. If you are investigating the spring in the lower roller on the Contax I it is wound the opposite direction to the spring in the Contax II and Kiev. There are no spares that I know of.

I replaced the roller in my 'I' with a roller and spring from a "II' by putting it in the other way round. This involved modifications to the camera itself but was a success.

Earlier in this thread someone described working on the spring that is in the roller, I think they may have been successful but it looked very fiddly to me.
The "thud" is Back! ..and the speed group selector works again.

Of course this took a little investigation into how the group speed selector works: The escapement mechanism was two feelers that exit the casting and engage with the cams under the speed group dial. The cams raise and drop these two levers and set the speed at which the curtain travels across the film gate; the speed selector dial then presets the gap between the curtains. So the issue was that the two feelers were not properly engaging in their slots.. pulled out some feeler gauges, caliper and needle nose pliers! Everything with the curtain travel speed works as it should.

Now off to the shutter shading at 1/500 and 1/1000...someone has been in here in the last 80 years....


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And the camera is back to functioning very well! (just 1/1000s shades due to the curtains not being 100% parallel).

Shutter accuracy:
  • 1/2 = 0.70s
  • 1/5 = 0.25s
  • 1/10 = 0.11s
  • 1/25 = 0.044s
  • 1/50 = 0.019s
  • 1/100 = 0.013s
  • 1/100 (sport) = 0.008s
  • 1/200 = 0.005s
  • 1/500 = 0.002s
  • 1/1000 = shades on on side.
So after having read Deklari's posts and observing the curtain gap (or lack of..) at high speed settings I dismantled the advance/shutter speed knob and from the film chamber pushed down the conical gear (of the advance knob) decoupling it from the upper roller and moved a couple of teeth until I had the correct gap (I aimed for about 1.5mm at 1/1000). This was a trial and error process that required the disassembly and reassembly of the advance knob several times. Interesting fact is that the conical gear is kept in place with minimal pressure so anytime the film advance/shutter knob is dismantled the synchronization with the top roller can be easily lost if not paying close attention. Note that the group speed selector can stay in place and it is not necessary to remove the front cover to do this. So this provides a simple way to adjust the shutter gap without touching the ribbons.

As far as my ribbons are concerned, the parallelism of the curtains becomes more and more critical as the gap becomes smaller, at 1/1000 even a 0.5mm difference can cause capping and/or different exposure across the film plane and I am assuming the quality and type of ribbons plays a big role here too.

Now all I need to do is load some film into it again; never forget that is the ultimate goal!

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I had success replacing the springs on a Contax 1(e) with those from a Kiev 4. The springs appeared to be identical to the Contax I springs. I did not notice any reversal in their arrangement, however the process was time consuming and to dismantle the Kiev part it was necessary to cut the axle, in particular for the removal of the center spring without damaging it beyond reuse. Since I had previously dismantled a Contax II bottom curtain unit I was familiar with what was necessary. It is too bad there is not a kit for the reuse of the Kiev in the Contax I bottom unit but that would require some milling and drilling but I think it can be done. The tensioning is just done from the opposite end. I am near Huntsville, Alabama where there is a machine shop, and I may just ask them if they have the capacity to do such a modification. Considering the number of available cameras I doubt it would be profitable. I have posted a recommendation to change out the small screws for the adjustment plate so that more threads are available to hold them while adjusting tension. The center spring brings down the 1st curtain, and it is smaller than the end springs which bring down curtain 2 however curtain 2 engages the escapements more so in the exposure process as far as I can tell so it would make sense to have larger springs pulling the ribbons attached to that curtain. [The picture of the "bee" was taken with the Contax 1(e) at the 1/1000 is an enlargement of course.]

My measurement of the ribbon thickness from the Contax I(e) I have worked on was 0.12 mm but the ribbon used as a replacement was 0.15 mm width which I think accounts for the slowness in the non sport speeds because of the increasing length of ribbon that passes through the clutch, friction. Can I adjust the clutch to improve performance? I may try it out and let you know.
The "Sports Speeds" are right on. The slow speed 1/2 or 0.50 is closer to 0.85 but the others are closer. I am using the CRT images in comparison to those from an Olympus OM-2 for the "Sport Speed" evaluation. It is amazing that the images show, from top to bottom, a parallelogram slanted to the right from top to bottom. I had previously described this as a rectangle but because of the slant the short sides at the top and bottom are not right angles. The width of the parallelogram on the Olympus and Contax I are very close to the same at the high speeds. However with the Olympus there is acceleration variation causing some curvature differences at the slower of the high speeds. I highly recommend using this simple technique if you do not have professional equipment. I found the technique on line used for Barnack type cameras.