Contax I ribbons

[Dralowid]

Just when you thought I had given up...

The tension setting side:

IMG_2862 by dralowid, on Flickr

I had some trouble getting the hole for the sliding plate in place but all now seems to work. It is positioned differently from Deklari's because the camera chassis casting gets in the way on mine. These screws have seen a lot of use and are on their last legs.

The other end:

IMG_2864 by dralowid, on Flickr

This needed a bit of thought to take account of the shorter axle on Contax II/Kiev. In the end I re-used a small bush from the original fitting and then put in a flat headed screw to one side of the axle to stop 'end float'. You may call me a butcher...

The roller is now in position and centralised. However, it is not the new Kiev roller. This is a dry run with the old Contax II roller before I install the new one.

A bit confused as to which ribbons to use, AA or Kiev (Kiev measures 0.32mm or 0.125"). Not that bothered about 1/1000!

What do you reckon?

 

[Grytpype]

A bit confused as to which ribbons to use, AA or Kiev (Kiev measures 0.32mm or 0.125").

If your Kiev ribbon measures .0125", personally, I'd give it a try. Is this the ribbon that came with the New Old Stock curtains?

My Arsenal ribbon was bought 'by the metre' from two different sources, and as I've said, both are in the .015"/.016" region. I wish I could lay my hands on a NOS roll of 'proper' Kiev ribbon!

 

[Dralowid]

Yes, it is the ribbon on the 'NOS' curtains. I am tempted to give it a go.

Two points:

1) it is already on the roller so I only have to do two attachments
2) Being from a Kiev it is long enough to give a little spare on the Contax I.

 

[Deklari]

Just when you thought I had given up...

The tension setting side:

IMG_2862 by dralowid, on Flickr

I had some trouble getting the hole for the sliding plate in place but all now seems to work. It is positioned differently from Deklari's because the camera chassis casting gets in the way on mine. These screws have seen a lot of use and are on their last legs.

The other end:

IMG_2864 by dralowid, on Flickr

This needed a bit of thought to take account of the shorter axle on Contax II/Kiev. In the end I re-used a small bush from the original fitting and then put in a flat headed screw to one side of the axle to stop 'end float'. You may call me a butcher...

The roller is now in position and centralised. However, it is not the new Kiev roller. This is a dry run with the old Contax II roller before I install the new one.

A bit confused as to which ribbons to use, AA or Kiev (Kiev measures 0.32mm or 0.125"). Not that bothered about 1/1000!

What do you reckon?

Good job Michael ! I have installed a new Kiev roller with AA ribbons (103mm). All "white"/fast speeds in "Sport group" works (I will check accuracy later). In "Normal group" only 1/25 and 1/50 works, but 1/100 doesn't (but I still have working 1/100 at "sport group"). All "red"/slow speed (included "B") have issue with second curtain (very slowly moving down). I have try to change the roller tension starting from 5 full rotation to 8 full rotation, I don't want to move higher. My guess; I need to clean slow speed escapement gears. Does anyone have any other suggestions?

 

[Sarcophilus Harrisii]

Yes, it is the ribbon on the 'NOS' curtains. I am tempted to give it a go.

Two points:

1) it is already on the roller so I only have to do two attachments
2) Being from a Kiev it is long enough to give a little spare on the Contax I.

As it seems (if I understand things correctly) that early Kievs had thinner ribbons than later ones then perhaps it depends on what vintage of Kiev your new assembly was made for and when it was made? I would be guided by ribbon thickness and condition. Later Kiev ribbons are known to be too thick for Contax II/III and I assume I, also. I would apply some tension to them with fingers to test for integrity if they are venerable. My first Contax II had ribbons which looked fine, but disintegrated when tensioned. I retained the remnants of it and two other examples. If you require details of them, measurements, etc.—let me know.
Cheers
Brett

 

[Dralowid]

Good job Michael ! I have installed a new Kiev roller with AA ribbons (103mm). All "white"/fast speeds in "Sport group" works (I will check accuracy later). In "Normal group" only 1/25 and 1/50 works, but 1/100 doesn't (but I still have working 1/100 at "sport group"). All "red"/slow speed (included "B") have issue with second curtain (very slowly moving down). I have try to change the roller tension starting from 5 full rotation to 8 full rotation, I don't want to move higher. My guess; I need to clean slow speed escapement gears. Does anyone have any other suggestions?

I have been told by Ed that if everything is correct a Contax II should work on a tension of five turns.

 

[Sarcophilus Harrisii]

Five to five and a half turns has been the sweet spot in 3 x Contax IIs I have replaced ribbons in. That is with shutter uncocked, and starting from when the initial slack in the curtains and ribbon drums has been taken up, for clarity.
Cheers
Brett

 

[Erik van Straten]

Good job Michael ! I have installed a new Kiev roller with AA ribbons (103mm). All "white"/fast speeds in "Sport group" works (I will check accuracy later). In "Normal group" only 1/25 and 1/50 works, but 1/100 doesn't (but I still have working 1/100 at "sport group"). All "red"/slow speed (included "B") have issue with second curtain (very slowly moving down). I have try to change the roller tension starting from 5 full rotation to 8 full rotation, I don't want to move higher. My guess; I need to clean slow speed escapement gears. Does anyone have any other suggestions?

Fantastic achievement!

Did you try a tiny little bit of watch oil on the spots on wich the spindles turn (no oil on the ribbons!)? The shutter needs lubrication.

Cleaning with benzine on an artists brush (sable) can help, but some lubrication afterwards is necessary.

You can give the second curtain extra tension when you turn the the ribbons a few times more around the rollers before they go into the friction clutches. This is the way to give a differentiation between the tension of the central spring (first curtain) and the tension of the springs of the side rollers (second curtain).

Can also be that there is friction against the cover plate.

Erik.

 

[Grytpype]

Five to five and a half turns has been the sweet spot in 3 x Contax IIs I have replaced ribbons in. That is with shutter uncocked, and starting from when the initial slack in the curtains and ribbon drums has been taken up, for clarity.
Cheers
Brett

I'd agree that 5 or 6 turns should be about right for a completely clean Contax II, but up to 8 should be safe. There is a bit of doubt in my mind about fitting the ribbons to their rollers and where you start counting turns.

I posted earlier in this thread that all the Contax and Kievs I had looked at showed about two turns of the ribbons on the rollers when the first curtain was fully extended, as pictured below:

​

This means that when you tension the shutter with it closed and in the uncocked position, the second curtain rollers springs will start to tension about one turn after the first curtain spring, which seems reasonable. There is no mention in Maizenberg, or any online source, of these two turns of "pre-tension", and the implication is that you would assemble the ribbons to their rollers as below:

​

This means that when you tension the shutter, by the time the slack in the ribbons has been taken up, and the rollers start to tension, there will already be at least three turns on the first curtain spring. If you tension by five turns from the point where the first curtain spring starts to tension, there will only be about two turns on the second curtain springs, which seems wrong to me, since the tension has to be able to drive the escapements.

The Kiev 2A I am working on now has contradicted my previous "two turns of pre-tension" statement. It resembles my second picture. Its fault was that, although very good at the fast speeds, all escapement speeds were a stop slow or more. A very thorough cleaning in situ, of the escapements, and application of watch oil, gave no improvent at all. I'm now reassembling after a total strip-down, but I wonder if it is possible that the problem might just have been the lack of second curtain tension. There is absolutely no sign that the curtains may have been replaced. I will be assembling with my usual 'two turns' on the rollers.

Of course I've no way of knowing how much, if any, of this can be applied to the Contax I!

Steve.

 

[Erik van Straten]

II wonder if it is possible that the problem might just have been the lack of second curtain tension.

Steve.

You can give the second curtain extra tension when you turn the the ribbons a few times more around the rollers before they go into the friction clutches. This is the way to give a differentiation between the tension of the central spring (first curtain) and the tension of the springs of the side rollers (second curtain).

Erik.

 

[Sarcophilus Harrisii]

I'd agree that 5 or 6 turns should be about right for a completely clean Contax II, but up to 8 should be safe. There is a bit of doubt in my mind about fitting the ribbons to their rollers and where you start counting turns.

I posted earlier in this thread that all the Contax and Kievs I had looked at showed about two turns of the ribbons on the rollers when the first curtain was fully extended, as pictured below:

​

This means that when you tension the shutter with it closed and in the uncocked position, the second curtain rollers springs will start to tension about one turn after the first curtain spring, which seems reasonable. There is no mention in Maizenberg, or any online source, of these two turns of "pre-tension", and the implication is that you would assemble the ribbons to their rollers as below:

​

This means that when you tension the shutter, by the time the slack in the ribbons has been taken up, and the rollers start to tension, there will already be at least three turns on the first curtain spring. If you tension by five turns from the point where the first curtain spring starts to tension, there will only be about two turns on the second curtain springs, which seems wrong to me, since the tension has to be able to drive the escapements.

The Kiev 2A I am working on now has contradicted my previous "two turns of pre-tension" statement. It resembles my second picture. Its fault was that, although very good at the fast speeds, all escapement speeds were a stop slow or more. A very thorough cleaning in situ, of the escapements, and application of watch oil, gave no improvent at all. I'm now reassembling after a total strip-down, but I wonder if it is possible that the problem might just have been the lack of second curtain tension. There is absolutely no sign that the curtains may have been replaced. I will be assembling with my usual 'two turns' on the rollers.

Of course I've no way of knowing how much, if any, of this can be applied to the Contax I!

Steve.

Hi Steve,
I can only say that I latch the curtains together, I keep the ribbons spooling around the drums as I take up the slack with the adjuster, and then, when the adjuster stiffens up as the springs begin to tension I give it three or four turns to begin with. At that point I will check the speeds and see how they're looking. If the clutches are still a bit loose I might detect some capping on 1/1250 or 1/500 because the ribbons are slipping. Once I've fine tuned this, I sometimes find that, on the slower speeds, the second curtain may not cap off and latch up reliably. (Incidentally it is important to check this point with the camera held in various positions, particularly upside down. It's eminently possible to think the shutter is fully functional at all the speeds and to then notice that, whilst the second may cap off acceptably with the camera held landscape and gravity helping it descend, if you invert it, the second then won't quite have the oompth needed to close and latch completely, when fighting gravity.) At that point, with the friction through the clutches good for the fast speeds, assuming the mechanism is clean and correctly lubricated, an extra turn or two (5 to 5 1/2 in total from takiing up ribbon slack) will get the slow speeds completing well at any orientation including 1/2 and Bulb.

I have run a few films through these that have produced good results. Including a roll of Fuji RDPIII specifically exposed at all the various shutter speeds, a film that isn't particularly forgiving in its exposure latitude, like most transparency types, so I think it's not too far away from spec, as I set exposure accurately with a reliable incident meter. I really must scan that roll soon. Hope this assists.
Cheers
Brett

 

[Dralowid]

Hmmm I've been pondering the issue of rolling up slack ribbon onto the drums, it is my next step.

When I first did the ribbons on this camera, I wound all the loose ribbon onto the rollers so that the shutter was, in effect, closed when un-tensioned and at rest, OK, so my first attempt did not work because the 1st blind spring was broken.
See the picture below:

IMG_2829 by dralowid, on Flickr

Now, the 'New Old Stock' Kiev shutter blind assembly, which came in its original packaging, was supplied completely open, see picture below:

IMG_2876 by dralowid, on Flickr

Three questions:

Winding all the ribbon slack onto the rollers did I over tension the second blind?

Am I to assume that a Kiev repairer would put this replacement part straight in and tension all three springs at the same rate?

(It is possible to wind a turn or two onto the rollers by turning the second roller through the space between the ribbons and twisting/creasing the ribbons to feed them through the clutches...can't explain it properly but I'm sure they didn't do it)

I quite like the idea of putting tapes around the rollers a couple of turns before feeding them through the friction clutches, it seems like a sensible compromise?

Opinions gentlemen please...

Michael

Oh, and of course, ribbon length affects tension. Contax I ribbons are about 10 mm shorter than Kiev/Contax II ones.
Shorter = more tension on the second blind.

 

[Dralowid]

Duplicate post, ignore!

 

[Erik van Straten]

I quite like the idea of putting tapes around the rollers a couple of turns before feeding them through the friction clutches, it seems like a sensible compromise?

There will be a difference between tension quality of a new set of springs and springs that are 80 year old. I would just start with the set how it is.

Erik.

 

[Deklari]

Fantastic achievement!

Did you try a tiny little bit of watch oil on the spots on wich the spindles turn (no oil on the ribbons!)? The shutter needs lubrication.

Cleaning with benzine on an artists brush (sable) can help, but some lubrication afterwards is necessary.

You can give the second curtain extra tension when you turn the the ribbons a few times more around the rollers before they go into the friction clutches. This is the way to give a differentiation between the tension of the central spring (first curtain) and the tension of the springs of the side rollers (second curtain).

Can also be that there is friction against the cover plate.

Erik.

Thanks Erik. Yes I did the second curtain extra tension as you suggested before.

 

[Grytpype]

You can give the second curtain extra tension when you turn the the ribbons a few times more around the rollers before they go into the friction clutches. This is the way to give a differentiation between the tension of the central spring (first curtain) and the tension of the springs of the side rollers (second curtain).

I apply my extra couple of turns by looping the ribbon round the 2nd curtain rollers before I slip the ribbon loop (already stitched) on to the roller - the only way you can do it if the ribbon is already through the friction slots and attached to the second curtain!

From Michaels picture of the NOS curtains it looks as though there should actually be no extra turns - that is if in the picture there is no tension at all on the ribbons between the rollers and the friction slots - and the curtains would certainly be supplied ready to fit.

 

[Erik van Straten]

From Michaels picture of the NOS curtains it looks as though there should actually be no extra turns - that is if in the picture there is no tension at all on the ribbons between the rollers and the friction slots - and the curtains would certainly be supplied ready to fit.

Yes, but they are new. What I say, is only supposition, mind you. Do the central spring and the springs at the sides in Contax I cameras still give the same tension as they did 80 years ago? Maybe there is now some difference between the tension of the second and the first curtain. I couldn't get my cameras at work without giving the second curtain some extra tension.

Erik.

 

[Dralowid]

Yes, but they are new. What I say, is only supposition, mind you. Do the central spring and the springs at the sides in Contax I cameras still give the same tension as they did 80 years ago? Maybe there is now some difference between the tension of the second and the first curtain. I couldn't get my cameras at work without giving the second curtain some extra tension.

Erik.

There is no tension in the shutter blinds shown in the picture. Remember that for this exercise I have to pull it apart anyway, those are Kiev blinds which obviously will not fit and need to be replaced with the Contax I ones. Question is, when I reassemble, shall I put a couple turns onto the rollers or not.

Erik suggests not because the springs are 'new' but Deklari has used what I think was a new roller and has had success with a couple of turns.

 

[Deklari]

There is no tension in the shutter blinds shown in the picture. Remember that for this exercise I have to pull it apart anyway, those are Kiev blinds which obviously will not fit and need to be replaced with the Contax I ones. Question is, when I reassemble, shall I put a couple turns onto the rollers or not.

Erik suggests not because the springs are 'new' but Deklari has used what I think was a new roller and has had success with a couple of turns.

I have used roller from 1980-old Kiev and make two ribbons turns before installation. I have trying many different tension settings, it looks like a few pre-turns will only help create correct tension.
Michael, you can try without pre- tension first. I guess you don't want to replace original ribbons. But you will need to install top roller correctly, what maybe not so easy.

 

[Deklari]

Can also be that there is friction against the cover plate.

Erik.[/quote]

I'm wondering if the cover plate has any type of spring on the back? I think is something missing on my plate.