HU:Aki Asahi Ribbons for Kiev Shutters

[ZorkiKat]

Two words: They work!

Five shutters brought back to life, courtesy of the $6.00 Aki-Asahi ribbons. (Still three dead Kiev, from other complications.)

The AA ribbons are very suitable substitutes for the Arsenal Ribbon. Being thinner, they should work on a Contax II/III as well (the AA ribbons have the same width and thickness quoted as the 'original' Zeiss silk ribbons in a certain Contax camera site ). The AA ribbon is likely Habutae silk, the same natural silk which Japanese camera makers used for their shutters cloths and tapes.

The only modification needed to be done (as suggested through a PM by a kind RFFer) on the Kiev shutter is to lightly bend the friction clutch (slots on the 1st curtain) to allow these to ride on the ribbons with some friction.

A "torture test" on the ribbons indicated no signs of wear or fraying even after the first 200 actuations. After the 800+th, the ribbons still look the same.

The AA ribbons don't need a "break-in" period too, to soften them. They will work as is, and tension need not be set high. About 5 turns or so should work, as opposed to the 8-10 needed for Arsenal Ribbons (per Maizenberg's instructions).

This is how the 'tortured' ribbon looks after more than 800 cycles:

The AA ribbon is available from http://aki-asahi.com/store/html/curtains/shutter-curtain.php. It does say that it is
"suitable for repairing old Contax cameras' shutter tape". It's only $6.00 for a 2 metre length, postage included.

Jay

 

[myequation]

I waiting on mine and look forward to trying.

Would love an update on your repairs?
are they still clicking away?

 

[ZorkiKat]

I waiting on mine and look forward to trying.

Would love an update on your repairs?
are they still clicking away?

Still working and going strong...and appears that they will remain that way for a long time.

The shutter's friction clutches must be pinched a bit so that they can grip the ribbons. Without this grip, the lower curtain will fall prematurely. This is noticed at speeds from 1/100 to 1/1250. When the shutter is fired, the lower curtain will drop too soon as a result of freely riding (instead of 'holding on) the ribbons, pulled by the central spring of the lower roller. The upper curtain is often detained for some time before it moves and exposure will be around 1/5 rather than 1/100.

Friction clutches which don't grip the ribbons right will also fall down too quickly when the shutter is being wound. This will put more strain on the pincers of the lower blind which grip on the upper blind to make sure that the gap between them is closed during winding.

The red arrows point to the friction clutches. The friction clutches in this shutter have been pinched in (by a wooden peg, lightly hammered) to grip on the thinner ribbon. The fiction clutch on Kiev shutters are more 'open' because the original Arsenal ribbons are much wider.

Don't pinch the clutches too tight though. Just enough to allow them to grip, but still glide on the ribbon when the lower curtain is pulled with a bit of force. If the curtain falls on its own due to gravity, the clutches are loose and aren't gripping properly.

 

[myequation]

very good info.

Did you bend the clutch on the Contax shutter also?
I believe there is a small difference between kiev and true contax ribbon specs.

 

[myequation]

nevermind i see that you explained this above.

thanks for the pics too, please post any that you have.

 

[myequation]

quick question,
How is the bottom drum attached to the slats? (other than ribbon)
I don't have one here at the moment.
I have a contax arriving in the mail that has a busted drum spring.
I was planning to replace it with a kiev/contax drum if possible.

 

[tkrap]

Contax I

Contax I

Hi,

did you ever repair any contax I using these ribons, I have one with broken ribons but I don't even know how to dissasemble it.

Thanks

 

[Dez]

The tape material on Contaxes and Kievs is extremely critical. I have succeeded in using this thin stuff, but it's tricky. The tape must have enough friction to keep the shutter from closing before the leading curtain is released when both curtains are rolled up on the upper roller. At the same time, it must not have too much friction or the trailing curtain will be slowed down after the leading curtain stops, leading to uneven exposures or failure to have the two curtains latch together.

The leading and trailing curtain have separate release mechanisms, and it is not possible to get the release to be exactly simultaneous. Typically the trailing curtain is released first, but stays in place due to sticktion in the tapes until the leading curtain starts to move.

The symptom of having too much friction is obvious- you can see that the trailing curtain slows down or does not latch properly.

The effect of too little is more difficult to see. The best way is to use the self-timer, remove the lens and look through the shutter aperture. If the camera releases the trailing curtain first and it moves on the upper roller you will get a blank exposure at speeds above 1/50. If the camera releases the leading curtain first and the tape does not hold, you will get a much-too-long exposure. You use the self-timer as it releases the shutter very slowly, and these problems are easily seen. You sometimes see advice to Contax/Kiev users to push the shutter button fast- this is why.

The solution is NOT to dial in lots of friction and increase the spring tension so the shutter closes regardless of the friction. You can make a Contax/Kiev work with different kinds of ribbon, but it needs to be carefully done. Be sure you check for both too much and too little friction before putting the camera back together again.

Cheers,
Dez

 

[Dez]

Hi,

did you ever repair any contax I using these ribons, I have one with broken ribons but I don't even know how to dissasemble it.

Thanks

I have overhauled a Contax 1A using these ribbons. This is the first model without slow speeds, which makes things more straightforward. It seems to be working well, but this is a very fragile camera, so gets treated very gently.





It is a tricky job, but doable. The later Contax 1's with slow speeds are a nightmare to service.

Cheers,
Dez

 

[Erik van Straten]

The later Contax 1's with slow speeds are a nightmare to service.

Those without slow speeds look better too. Very nice camera, Dez! I like that Tessar 50mm f/3.5 too. It seems that the majority of the Contax I cameras is fitted with the 50mm f/2.8.

Erik.