Copal MXV Shutter Speed Help

Discussion in 'Medium Format' started by dave_gardner|1, Feb 28, 2017.

  1. Hello,
    I'm working on trying to resurrect an old Yashica-mat TLR camera. Everything on the camera seems to be in pretty good shape, except that the shutter blades were gunked up with old oil. So, I ran the shutter through my ultrasonic cleaner with naphtha, then followed the instructions below to disassemble the shutter and make sure everything is clean inside.

    Once it was back together I ultrasoniced it 1 more time to make sure everything was clean and I didn't contaminate the blades, then let the naphtha dry overnight. It's clean and shiny now! The shutter blades open and close quickly too. The only issue is that the speeds are off.

    Using the microphone on my computer I timed the shutter speeds. The fastest speed I can measure is 1/50 of a second. All the speeds do seem VERY repeatable, just too slow. The four slowest speeds are on the slow range of the speed regulator, by the way, and then 1/25 and 1/50 are on the high-speed setting, so both modes do both seem off.

    (low speed)
    1s setting takes 1.92s
    1/2s setting is 0.967s
    1/5s setting (0.2s) is 0.366s
    1/10s setting (0.1s) is 0.135s

    (high speed)
    1/25s (0.04s) is 0.128s
    1/50s (0.02s) is 0.041s

    So, what can I do here? Is there a way to adjust the speed of the speed regulator to fix the speeds? Unfortunately I'd need to adjust both the high and low speed modes. Or do I just need some sort of lubricant on the speed regulator it for it to run faster? Right now everything is dry and free of solvent/grease (what you see on the blades appears to be some issue with the plating on the metal). I've reassembled the shutter back to where I'm ready to reattach the speed cam.

    Thanks for your help!!

    Last edited: Feb 28, 2017
  2. I don't know what you mean "Using the microphone on my computer I timed the shutter speeds." There use to be a good thread on this site before the "overhaul" about using a photo transistor tester to test shutter speeds. I had updated it to currently available (2012) infrared led photo transistor but that thread is now ancient history and the current "we think you're looking for this" POS search engine is a complete waste of time. The tester can still be found at

    A drop of clock oil or similar light weight machine oil about the size of a straight pin point on the gear shafts of the timing delay and other movements may help. Too much lube acts like glue. Servicing guides say to "wipe off the excess leaving a light sheen of oil".
    Some shutters have an adjustable delay gearing. The closer the pallet end (furthest from the cocking lever) is to the center of the shutter the faster the slow speeds, set for correct 1 second. The release end (closest to the cocking lever) is fastest when closer to the outer side of the case.

    The delay timing control speeds from 1 second to 1/125, faster speeds are achieved with booster speeds.
    The shutter may nor run correct speeds until fully assembled.
  3. What I mean by the microphone is... when the shutter is triggered on a longer speed setting there is a loud click as the blades open, then a quieter buzzing noise of the speed regulator, then another loud click as the blades close. So I just recorded this sound on my computer and used some audio recording software to see how long the time was between the two loud clicks.

    I can try the oil idea, I can always clean it off again with the naphtha if needed.

    When you say the "pallet end" which part is that? Is it the black u-shaped piece that "wiggles" on the gear when the speed regulator runs? (I uploaded the image again with an arrow by the part I'm talking about). And by changing the position, are you talking about moving the whole speed regulator, or moving this part within the speed regulator. This is definitely the part where I have questions regarding how to change the speed.

  4. p.s. you mention "the overhaul"...this site seems to be completely redone since the last time I posted on here...what's with that? All of the line breaks in my posts seem to not show up so my message looks like one giant run-on paragraph. :( Did they get rid of the archive of posts on this forum? There was a wealth of really great older information there...
  5. How can you test the speeds with the speed cam removed? The speed cam alters the meshing of the regulator train with the blade ring-gear or toothed sector. Nothing will measure correctly without the cam in place.<p><br>
    The dark areas on the shutter blades look like remnant oil to me. I've always stripped a shutter down to where the blades can be removed and de-greased separately. Then wiped dry with absorbent tissue.<p><br>I also have doubts about relying on a sound signal to measure the faster shutter speeds. A photodiode or phototransistor is definitely the way to do it properly. Maybe a photodiode could simply be hooked up to the mic input of a computer. Should be good from a fraction of a millisecond down to maybe 1/20th of a second. Although you might have to hunt for the blip on the sound trace.
    Last edited: Mar 1, 2017
  6. I should have been more clear, I did replace the speed cam to test the speeds, I just currently have it off. Also I did strip the shutter down completely and removed/cleaned the individual blades. I can guarantee there is no oil/grease/residue on the blades. The discoloring appears to be a little discoloring or corrosion to the finish of the metal.

    I'll see if I can rig up some sort of optical speed tester...
  7. The whole delay mechanism moves, the green arrow end is the pallet end, adjust it if possible for 1 second, the regulator end (the other end) is adjusted for 1/30.
    I have not had the opportunity to work on Copal shutters. There may not be any adjustment room in the delay mount.
    A microphone next to the case will not be accurate for speed timing. The shutter speed tester I referenced produces a spike at shutter opening and another at shutter closing. If the time line is expanded the spike becomes a curved ramp. Speed measurement is from start of rise to start of fall. I have tested speeds of 1/1000 with it.
    My laser pointer failed so I put a piece of dark red light filter over the sensor and use standard AA maglight for leaf shutters and a CFL for focal plane shutters.
    The red filter is close to a Wratten 25. The LED sensor is placed at the center of the shutter opening.

    Hold the shutter so you can see the shutter blades and the second hand of a clock or watch. ( puts one on your desktop.) Set the shutter , release the shutter just as the second hand reaches a second mark. The shutter should fully open within .0001 to .0003 second and fully close just as the second hand reaches the next second mark. Set the speed to 1/2 second and repeat. The shutter should close just as the second hand reaches the mid point between the starting and next second marks. A sweep second hand movement works better than a quartz step movement for 1/2 second. The second hand width either side of the desired position on shutter close is in tolerance.
  8. I added some oil to the speed regulator (labeled "Turbine Oil") to see if that would increase the speed. I can always remove it with the Naphtha if needed. Now I'm measuring somewhat faster speeds, although not quite fast enough:
    1s = 1.35s
    1/2s = 0.7s
    1/5s = 0.289s

    So, do I need a lighter oil? (this stuff seems light but not as thin as water) Or, is there a way I can adjust the speed that the speed regulator runs at?

    I'm still working on a way to more accurately measure the fast speeds...

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