Contax I ribbons

Dralowid said:
Deklari, Interesting read, many thanks!

So now we know that those of us that don't have the later brass shutter blinds have duraluminum blinds, not cheapy old aluminium...whatever the difference may be!
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"Duralumin" was a German invention, a way to harden aluminium. It was used in particular in the aircraft industry.

Erik.
 
Erik van Straten said:
"Duralumin" was a German invention, a way to harden aluminium. It was used in particular in the aircraft industry.
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And in the cycling industry, first for bikes components (handlebars, stems, brakes calipers, drivetrain cranksets, derailleurs, rims, seatposts), and, later, whole bikes frames (but there, the special steel and carbon tubing techniques proved to remain better : many duralumin frames may break over time).
 
this is gif. file showing how shutter works
https://ru.wikipedia.org/wiki/%D0%A4%D0%BE%D1%82%D0%BE%D0%B3%D1%80%D0%B0%D1%84%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B9_%D0%B7%D0%B0%D1%82%D0%B2%D0%BE%D1%80#/media/File:Appearance_of_the_shutter_at_various_speeds.gif

If fast speed pre-sett and window between curtains is correct, what will influence on the shutter speed? I can only see friction of curtains in shutter and tension of the spring. I trying to understate why at 1/1000 I only have 1/300. I have change tension.. no change in speed. I have remove cover (to avoid friction).. same speed.. What do I missing?
 
At the high speeds (sports group) ONLY the slit between the curtains change. At 1/1000 the slit is only a few millimeters (about 3mm I've read somewere), at 1/500 twice as large etc.

Erik.
 
Erik van Straten said:
I took a look. The teeth of the fork to rewind the film in v5 are different and longer than those in my other Contax I's. I think those teeth are the problem.

Erik.
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Very interesting Erik we have spurred you on with all this, and I use the word as praise, tinkering. It is possible that part was replaced at some stage in its life possibly with a partially non compatible part or is it fitted correctly? Hard to see they would break ( as some did on the Nikon F100 early series, plastic in that case of course).

I don't want to wander OT further but what happens with the Kievs? Do they have the sprocket problem, could you obtain a donor part?
 
Deklari said:
I trying to understate why at 1/1000 I only have 1/300. I have change tension.. no change in speed. I have remove cover (to avoid friction).. same speed.. What do I missing?
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In the sports group (1/1000, 1/500, 1/200, 1/100) the gears are disconnected. The spring power is maximum. That is why there is much more shutter noise than in the other groups. The springs run free. When you set the speed, only the slit changes.

Erik.
 
Erik van Straten said:
In the sports group (1/1000, 1/500, 1/200, 1/100) the gears are disconnected. The spring power is maximum. That is why there is much more shutter noise than in the other groups. The springs run free. When you set the speed, only the slit changes.
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Yes indeed. So getting 1/300 instead of something closer to 1/1000 can be explained by two reasons only :

- the slit is too wide,
- the 1st curtain roller drum springs are too weak.

In case of a slit being too wide then it will be a mess to fix it because it's related to how the 1st and 2nd curtains are synchronized.

In case of something odd under the shutter cover was braking the 1st curtain, or the 1st curtain drum roller brake (the piece of leather glued on the drum) misbehaving, then you would have uneven exposure with, possibly, some shutter bounce or shutter capping (as a result a large part of the frame wouldn't be exposed).

Overtensioning the shutter drum roller springs often leads, as a famous paradox of both the prewar and postwar Contax shutters, to overexposure at high speeds, instead of underexposure at high speeds. The key of the plot is to tension the springs by the minimum amount so that 1/1000 (or 1/1250 on the Contax II and IIa shutter) and 1/25 are, at the same time, as close as what they can be to their optimum siblings according to the shutter speeds tester.
 
Sorry not to have been keeping up with this, had a small operation yesterday to mend things...having been lifting up too many boats, will get back to the Contax shutter as part of my convalescence but there is always a chance that rage and infuriation may split my stitches!

Three cheers for the long suffering National Health Service here, and what is more, the anaesthetist actually knew what a Contax was but the conversation came to an end when I fell asleep!
 
Highway 61 said:
Yes indeed. So getting 1/300 instead of something closer to 1/1000 can be explained by two reasons only :

- the slit is too wide,
- the 1st curtain roller drum springs are too weak.

In case of a slit being too wide then it will be a mess to fix it because it's related to how the 1st and 2nd curtains are synchronized.

In case of something odd under the shutter cover was braking the 1st curtain, or the 1st curtain drum roller brake (the piece of leather glued on the drum) misbehaving, then you would have uneven exposure with, possibly, some shutter bounce or shutter capping (as a result a large part of the frame wouldn't be exposed).

Overtensioning the shutter drum roller springs often leads, as a famous paradox of both the prewar and postwar Contax shutters, to overexposure at high speeds, instead of underexposure at high speeds. The key of the plot is to tension the springs by the minimum amount so that 1/1000 (or 1/1250 on the Contax II and IIa shutter) and 1/25 are, at the same time, as close as what they can be to their optimum siblings according to the shutter speeds tester.
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Thanks for explanation
this what I observed the slit is too wide for 1/1000. I have looked how mach it in my Contax III, it defiantly more than 3mm (as Erik mention). Because in my Cointax I the film-wind knob is missing, and I don't have any idea how this camera work and maintained before. It is possible what someone mess with curtains synchronization.
 
Highway 61 said:
the 1st curtain drum roller brake (the piece of leather glued on the drum)
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The glued piece of leather is actually not a break, but a sort of "exposure corrector". It opens the first curtain a little bit more in the second part of its run, otherwise the top of the picture would be underexposed. It "thickens" the axle on wich the curtain is wound. It slows down the speed of the first curtain a bit, but it is not a break like the break in an M Leica for instance; it is there for another purpose.

Michael, I hope you'll be better soon!

Erik.
 
Erik van Straten said:
The glued piece of leather is actually not a brake, but a sort of "exposure corrector". It opens the first curtain a little bit more in the second part of its run, otherwise the top of the picture would be underexposed. It "thickens" the axle on wich the curtain is wound. It slows down the speed of the first curtain a bit, but it is not a brake like the brake in an M Leica for instance; it is there for another purpose.
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Thanks for clarifying Erik. Yet, as there were some debates about the material used for this in the Contax vs the Kiev (leather on the Contax shutter, felt on the Kiev shutter), it seems that using that part from a Kiev origin (felt) may possibly make a Contax shutter misbehave, because the Contax shutter blinds are not of the same thickness as some Kiev shutter blinds.

I haven't tested this myself. I used several Kiev 1st curtain bottom rollers with good springs to successfully fix some Contax II shutters, but always re-used the original piece of leather taken off the defective Contax drum roller, instead of leaving the Kiev felt piece in place.
 
Highway 61 said:
Thanks for clarifying Erik. Yet, as there were some debates about the material used for this in the Contax vs the Kiev (leather on the Contax shutter, felt on the Kiev shutter), it seems that using that part from a Kiev origin (felt) may possibly make a Contax shutter misbehave, because the Contax shutter blinds are not of the same thickness as some Kiev shutter blinds.

I haven't tested this myself. I used several Kiev 1st curtain bottom rollers with good springs to successfully fix some Contax II shutters, but always re-used the original piece of leather taken off the defective Contax drum roller, instead of leaving the Kiev felt piece in place.
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The original Contax 'lifting heel' is black leather and the Kiev one seems to be a white imitation leather, with a sort of brushed surface. Could easily be mistaken for dense felt. Thickness is approximately the same. The only significant difference I can see is that the Contax one is chamfered at its leading edge whereas the Kiev one isn't.

I would suggest that there is perhaps not an awful lot of precision to this and so long as it is there it does its job.

I fear that the mysteries of blind synchronisation and gearing need to be understood, at least in part...
 
Dralowid said:
The original Contax 'lifting heel' is black leather and the Kiev one seems to be a white imitation leather, with a sort of brushed surface. Could easily be mistaken for dense felt. Thickness is approximately the same. The only significant difference I can see is that the Contax one is chamfered at its leading edge whereas the Kiev one isn't.
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All the Contax "lifting heels" are indeed made of black leather with chamfered leading edges.

I have seen many variations of that Kiev part. Some were red or purple, and clearly made of dense felt, not of some faux leather.
 
Highway 61 said:
All the Contax "lifting heels" are indeed made of black leather with chamfered leading edges.

I have seen many variations of that Kiev part. Some were red or purple, and clearly made of dense felt, not of some faux leather.
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One of my Kiev with s/n 543... (1954?) with faux leather exactly as on Contax, a second Kiev from 1980, as Michael described with white imitation leather. Early Kiev is a better copy of Contax.
 
Finally first shot...
img526.jpg

I figured out how to adjusted high speed. It is very long process. Not recommended to go there. But it may be interesting to understand how actually Contax I works.
I had a problem winding film after 25-26 shots. I had to unload in the darkroom. I have found a broken film perforations. I think it is issue with incorrect plastic spool I have used.
 
Congratulations with your first picture! Looks very nice. What lens do you use?

I am very curious how you managed to adjust the high speeds, Deklari. Very interesting. Can you give us a small indication how you did it?

Erik.
 
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