FED 1 shutter alignment issue

[sepha.kay]

Hello, I hope everyone is doing okay. I have an issue I'd like to discuss.

I'm working on a FED 1 at the moment, but there seems to be an issue with the alignment of the shutter, and by alignment I am referring to the curtain gap of the shutter as it travels. And no, It has nothing to do with the adjustment of the roller springs, but more of a mechanical issue, I believe. As I check the curtain gap on the shutter at 1/500 (by rotating the drum with my fingers), it starts as normal and decreases in size as it travels towards the right, so when I release the shutter, the gap increases as it finishes its travel. It is almost impossible to calibrate the shutter when this problem is present. Never had this sort of issue with other cameras and Zorki's. What could be the issue? I have attached sample images below. The drum and pawl are in the correct position. You can tell since the pawl is between the latch when cocked. I have also tried shifting the drum gear one tooth up, but still no luck.

Any help would be much appreciated, thank you for your time.

 

[sepha.kay]

Some more images...

 

[johnf04]

Have the shutter ribbons been changed? Are they too thick?

 

[sepha.kay]

Have the shutter ribbons been changed? Are they too thick?

Of course, I have changed them. They are very thin, about 0.15mm. Highly doubt it has anything to do with the thickness of the ribbons. Nothing is jamming etc. I use these all the time, never had a problem

 

[Ko.Fe.]

Here is all what you need:
https://www.fedka.com/jay/index_files/Page455.htm

 

[Sarcophilus Harrisii]

Within limits, you want the gap to increase across the gate. It offsets the reduction in exposure caused by the curtains accelerating as they run. It's only going to be an issue if the curtains are not balanced and the first is pulling away too much. Assuming a clean, lubricated, mechanism, adjusting spring tension should correct this. Get the amount of exposure consistent across the gate and then—if it is needed, and the adjustment is available—fine tune the second curtain release timing to correct the initial slit width.

 

[sepha.kay]

Here is all what you need:
https://www.fedka.com/jay/index_files/Page455.htm

Thank you, but this does not help since I know how to do all this. The problem is not listed here, nor anywhere else.

 

[sepha.kay]

Within limits, you want the gap to increase across the gate. It offsets the reduction in exposure caused by the curtains accelerating as they run. It's only going to be an issue if the curtains are not balanced and the first is pulling away too much. Assuming a clean, lubricated, mechanism, adjusting spring tension should correct this. Get the amount of exposure consistent across the gate and then—if it is needed, and the adjustment is available—fine tune the second curtain release timing to correct the initial slit width.

The curtains will be replaced with better ones after I resolve the issue. They are new, but not what I want in the camera. The camera runs really smooth however. I put it together myself. It came in bags... I cleaned everything, even the drum and roller springs, and lubricated them as needed. I tried adjusting the shutter many times especially visually via camera, but it's always capping or the slit is always starting out super thin then increasing dramatically. There's no way to even them out this way. I've worked on many cameras and I just recently finished a Zorki 1c (cleaned, new curtains, adjusted etc), but never had this sort of issue ever.

 

[Sarcophilus Harrisii]

In that case I'm wondering if these new curtains and/or ribbons have incorrect dimensions? If the mechanism and its curtains are to spec, it should be possible to balance the exposure across the gate by adjusting the spring tensions. As you've said this is not possible I'm wondering if the rest positions of the curtain laths are too far away from optimum. Not being able to inspect the camera in person that's the best I can do. How are you measuring exposure across the gate? A two or three sensor set up to measure exposure at start, middle and end of the gate is a great help.

 

[sepha.kay]

In that case I'm wondering if these new curtains and/or ribbons have incorrect dimensions? If the mechanism and its curtains are to spec, it should be possible to balance the exposure across the gate by adjusting the spring tensions. As you've said this is not possible I'm wondering if the rest positions of the curtain laths are too far away from optimum. Not being able to inspect the camera in person that's the best I can do. How are you measuring exposure across the gate? A two or three sensor set up to measure exposure at start, middle and end of the gate is a great help.

Well, when I measured the ribbons they were about 11.5cm or more, something around that range, but generally they should be about 10cm for each curtain. This is the measurement which I've been using for the last couple of years with no issues. Technically speaking, even if I were to use the original 11-12cm of ribbon for each curtain, the resting positions would still be the same. I would just need to shift them up on the rollers, meaning they'll overlap a little more, but still be where I need them to. The curtains on the other hand were way beyond damaged, so it wasn't possible to get any measurements. I went with the general long curtain being 10cm, short curtain being 7.5cm. I guess I can try shifting the closing curtain and opening curtain ribbons around some to change their resting position, but highly doubt it'll do the trick... it's just very weird. They should both be moving at the same pace when I rotate the drum with my fingers, even if the slit was wrong (wider or thinner). The slit at the moment is about 0.6mm, but loses about 0.1mm towards the end, or widens as it's being released, vice versa....

 

[sepha.kay]

Does any one know the original curtain and ribbon dimensions for the Fed 1?



Edit;


I decided that I will increase the ribbon dimensions for the opening curtain about 1.5mm more to decelerate the travel time, that being 11.5cm rather than 10cm. If this does not work I will cut new curtains, so instead of 10cm and 7.5cm for the closing and opening curtains they will be about 11 and 8 centimeters. I guess I can correct the lengths later as I test the shutter. If anyone else any other ideas please let me know. I will report back with my results as soon as I am done.