monopix
Cam repairer
I'm looking for any information on servicing the above and/or adjusting the speeds. I have a couple that are slow on the top speeds.
Any info appreciated.
Sent from my iPhone using Tapatalk
Any info appreciated.
Sent from my iPhone using Tapatalk
monopix
Cam repairer
Lots of views but no answers. I dove in and played.
Results here: deleted
Results here: deleted
Last edited:
R
rick oleson
Guest
I have notes for disassembly and shutter blade replacement on the FM2n... it doesn't address adjustment but it gets you inside the camera to where you have to go. Email me for a copy at rick.oleson@gmail.com
monopix
Cam repairer
monopix
Cam repairer
NOTE:
THE IMAGES IN THIS POST KEEP GETTING LOST SO I'VE NOW POSTED THIS ON MY BLOG AT:
Contax S2 shutter adjustment
IT HAS BEEN UPDATED AND HAS HAD THE NIKON REFERENCES REMOVED BUT IT HAS THE SAME INFORMATION.
This is a rewrite of my original post due to the pictures going missing and to include more information that I've learnt since writing the original. Some of the pictures are of other, similar, shutters so may not be exactly as you find in the camera.
The Nikon FM2 shutter is a mechanical shutter with speeds from 1 sec. to 1/4000 sec. plus B plus an extra speed of 1/200 sec. which was the original flash sync. speed of the camera. It originally used titanium blades which were etched with a honeycombe pattern to lighten them. Later, after some improvements were made, it was possible to achieve flash sync. at 1/250 sec. so the 1/200 sec. position was blocked off though still exists. Later still, the blades were replaced with aluminium alloy types which have a smooth finish instead of the honeycombe pattern.
The shutter is made by Copal and is a variant of the Copal square shutter though Nikon appear to claim to be the developers of it.
The same shutter was used in the Contax S2 introduced in 1992 which was after the aluminium alloy blades were introduced so none of the Contax cameras have the honeycombe patterned blades. A variant of the shutter was also used in the Yashica FX-3 and some other Cosina made cameras, initially with speeds only up to 1/1000 sec. but later up to 1/2000 sec.
The shutter curtains are released by a cam rotating around a shaft driven by a spring. The spring has a small amount of adjustment to its tension. The position of the cam at which the second curtain is released is fixed but the position at which the first curtain is released is moved when changing speeds. This is the only method used to adjust between the top four speeds (1/500 - 1/4000 sec.). slower speeds use an escapement and a number of linkages to hinder the rotation of the cam and so decrease the shutter speed. The two curtains are driven by individual springs each with its own tensioner. Once the curtains are released, they travel independantly and have no interaction.
As mentioned, the main spring has some adjustment which will cause the main shaft to rotate more or less quickly. This affects all shutter speeds but the affect is mostly to the slow speeds with minimal affect to the high speeds.
There is an adjustment that alters the timing between the release of the first and second curtains. This affects the high speeds with no affect to the slow speeds.
The curtain tensions can also be altered to increase or decrease the travel time - this will also affect the high speeds with no affect of the slow speeds.
Adjustment of the main spring should be possible with the shutter in-situ (my experience from working on Contax S2 cameras, Nikons may be different) but any other adjustment requires the shutter to be removed from the camera. Image 1 shows the main operating levers that will be used to cock and trip the shutter if it's removed from the camera.
Image 2 shows the location of the adjustments.
Image 3 shows the location of the curtain springs and the slow speed escapement.
When adjusting the shutter, adjust for the slow speeds first, then the high speeds. Only adjust the curtain tensions if absolutely necessary as it can be difficult to get both curtains to run at equal speeds - necessary to prevent tapering. Note that this is a mechanical shutter and the speeds will not be perfect. All the speeds should be checked after each adjustment and some compromise may be necessary to get all speeds to within acceptable limits.
The main shaft has a disk attached to the top with a number of slots in it. The end of the main spring sits in one of these slots. See image 4. To adjust the slow speeds, move the end of the main spring to a different slot to either increase or decrease the tension as required. I've found the fingers forming the slots get pinched together by the factory to stop the spring end from slipping out so the fingers need straightening first to allow the spring to be moved. A flat bladed screwdriver pushed between the fingers usually does it. BEFORE moving the spring, wedge the tip of a screwdriver behind the spring end so that, if it slips out of the slot or you lose your grip on it, it won't fully unwind.
Note: The disk on the top of the main shaft that has the slots in it has a slotted hole that fits over a matching raised part on the end of the shaft. In theory, it would be possible to remove the disk and refit it turned by 180 degrees. See image 5. This would allow the spring to be tensioned an extra half-turn. I've never had to do that but if a spring was particularly weak, it might be a solution. The screw holding the disk in place is left hand threaded so turn clockwise to unscrew.
To adjust the high speeds, remove the shutter from the camera. Look for the high speed adjuster. See images 2 (above) and 6. It looks like the head of a screw with a slot in it but it's only visible side-on and the slot may not be facing you so may not be visible. Because it's not possible to engage a scewdriver in the slot in the normal way, it's necessary to use the tip of a flat bladed screwdriver pushed sideways into the slot to turn it.
If the slot isn't facing you then you need a screwdriver with the tip bent 90 degrees to get into the slot. See image 7. Only a very small movement is required.
Just to reiterate, check all the high speeds after adjusting the high speed ajuster and check all the slow speeds after adjusting the main spring as a compromise may need to be made. Image 8 shows the typical speeds after adjustment. I fire the shutter six times at each speed and plot the highest and lowest values to check for consistancy. This was a good shutter - you may not get the speeds this close to ideal. But they should be within the upper and lower limits (red and green lines). Note that 1/250th (flash sync speed) has it's tolerance all on the over-exposure side because, if it runs high (under-exposure) then cut-off may happen when using flash.
THE IMAGES IN THIS POST KEEP GETTING LOST SO I'VE NOW POSTED THIS ON MY BLOG AT:
Contax S2 shutter adjustment
IT HAS BEEN UPDATED AND HAS HAD THE NIKON REFERENCES REMOVED BUT IT HAS THE SAME INFORMATION.
This is a rewrite of my original post due to the pictures going missing and to include more information that I've learnt since writing the original. Some of the pictures are of other, similar, shutters so may not be exactly as you find in the camera.
The Nikon FM2 shutter is a mechanical shutter with speeds from 1 sec. to 1/4000 sec. plus B plus an extra speed of 1/200 sec. which was the original flash sync. speed of the camera. It originally used titanium blades which were etched with a honeycombe pattern to lighten them. Later, after some improvements were made, it was possible to achieve flash sync. at 1/250 sec. so the 1/200 sec. position was blocked off though still exists. Later still, the blades were replaced with aluminium alloy types which have a smooth finish instead of the honeycombe pattern.
The shutter is made by Copal and is a variant of the Copal square shutter though Nikon appear to claim to be the developers of it.
The same shutter was used in the Contax S2 introduced in 1992 which was after the aluminium alloy blades were introduced so none of the Contax cameras have the honeycombe patterned blades. A variant of the shutter was also used in the Yashica FX-3 and some other Cosina made cameras, initially with speeds only up to 1/1000 sec. but later up to 1/2000 sec.
The shutter curtains are released by a cam rotating around a shaft driven by a spring. The spring has a small amount of adjustment to its tension. The position of the cam at which the second curtain is released is fixed but the position at which the first curtain is released is moved when changing speeds. This is the only method used to adjust between the top four speeds (1/500 - 1/4000 sec.). slower speeds use an escapement and a number of linkages to hinder the rotation of the cam and so decrease the shutter speed. The two curtains are driven by individual springs each with its own tensioner. Once the curtains are released, they travel independantly and have no interaction.
As mentioned, the main spring has some adjustment which will cause the main shaft to rotate more or less quickly. This affects all shutter speeds but the affect is mostly to the slow speeds with minimal affect to the high speeds.
There is an adjustment that alters the timing between the release of the first and second curtains. This affects the high speeds with no affect to the slow speeds.
The curtain tensions can also be altered to increase or decrease the travel time - this will also affect the high speeds with no affect of the slow speeds.
Adjustment of the main spring should be possible with the shutter in-situ (my experience from working on Contax S2 cameras, Nikons may be different) but any other adjustment requires the shutter to be removed from the camera. Image 1 shows the main operating levers that will be used to cock and trip the shutter if it's removed from the camera.
Image 2 shows the location of the adjustments.
Image 3 shows the location of the curtain springs and the slow speed escapement.
When adjusting the shutter, adjust for the slow speeds first, then the high speeds. Only adjust the curtain tensions if absolutely necessary as it can be difficult to get both curtains to run at equal speeds - necessary to prevent tapering. Note that this is a mechanical shutter and the speeds will not be perfect. All the speeds should be checked after each adjustment and some compromise may be necessary to get all speeds to within acceptable limits.
The main shaft has a disk attached to the top with a number of slots in it. The end of the main spring sits in one of these slots. See image 4. To adjust the slow speeds, move the end of the main spring to a different slot to either increase or decrease the tension as required. I've found the fingers forming the slots get pinched together by the factory to stop the spring end from slipping out so the fingers need straightening first to allow the spring to be moved. A flat bladed screwdriver pushed between the fingers usually does it. BEFORE moving the spring, wedge the tip of a screwdriver behind the spring end so that, if it slips out of the slot or you lose your grip on it, it won't fully unwind.
Note: The disk on the top of the main shaft that has the slots in it has a slotted hole that fits over a matching raised part on the end of the shaft. In theory, it would be possible to remove the disk and refit it turned by 180 degrees. See image 5. This would allow the spring to be tensioned an extra half-turn. I've never had to do that but if a spring was particularly weak, it might be a solution. The screw holding the disk in place is left hand threaded so turn clockwise to unscrew.
To adjust the high speeds, remove the shutter from the camera. Look for the high speed adjuster. See images 2 (above) and 6. It looks like the head of a screw with a slot in it but it's only visible side-on and the slot may not be facing you so may not be visible. Because it's not possible to engage a scewdriver in the slot in the normal way, it's necessary to use the tip of a flat bladed screwdriver pushed sideways into the slot to turn it.
If the slot isn't facing you then you need a screwdriver with the tip bent 90 degrees to get into the slot. See image 7. Only a very small movement is required.
Just to reiterate, check all the high speeds after adjusting the high speed ajuster and check all the slow speeds after adjusting the main spring as a compromise may need to be made. Image 8 shows the typical speeds after adjustment. I fire the shutter six times at each speed and plot the highest and lowest values to check for consistancy. This was a good shutter - you may not get the speeds this close to ideal. But they should be within the upper and lower limits (red and green lines). Note that 1/250th (flash sync speed) has it's tolerance all on the over-exposure side because, if it runs high (under-exposure) then cut-off may happen when using flash.
Last edited:
Huss
Veteran
Wow, not just an excellent write up but also great pictures to illustrate it.
Ronald M
Veteran
Not for me. Repairman is in order.
monopix
Cam repairer
I might add to my original post that the shutter has to be removed from the camera to do any of this as the relevant parts are not accessible with the shutter in the camera.
seany65
Well-known
Don'tcha wish we still used lens caps to expose the film?
A great and well illustrated write up, Peter, thanks for that! I don't usually work on Nikons myself, but this will be invaluable to anyone who encounters the same issue you have had to remedy.
Cheers,
Brett
Cheers,
Brett
Huss
Veteran
You can still do that. Camera on B, lens cap on, lens cap off, lens cap on.
A little tricky to achieve that 1/4000 sec speed though.
R
rick oleson
Guest
yeah, i find that my maximum speed seems to slow down as i get older....
k2adir
Newbie
I know it's been a while but, is there any chance that you reupload some of these images back?
I'm having a similar problem with the FM2 I just took apart recently. I couldnt make the 1 second exposure faster than 1.48 secs
You can also send me a privite message, I couldnt send it to you.
thanks
I'm having a similar problem with the FM2 I just took apart recently. I couldnt make the 1 second exposure faster than 1.48 secs
You can also send me a privite message, I couldnt send it to you.
thanks
The post linked to above on my website has got deleted so I'm reposting it here.
-------------
Nikon FM2 Shutter
The Nikon FM2 shutter is a mechanical shutter with speeds from 1 sec. to 1/4000 sec. plus B plus an extra speed of 1/200 sec. which was the original flash sync. speed of the camera. It originally used titanium blades which were etched with a honeycombe pattern to lighten them. Later, after some improvements were made, it was possible to achieve flash sync. at 1/250 sec. so the 1/200 sec. position was blocked off though still exists. Later still, the blades were replaced with aluminium alloy types which have a smooth finish instead of the honeycombe pattern.
The shutter is made by Copal and is a variant of the Copal square shutter though Nikon appear to claim to be the developers of it.
The same shutter was used in the Contax S2 introduced in 1992 which was after the aluminium alloy blades were introduced so none of the Contax cameras had the honeycombe patterned blades. A variant of the shutter was also used in the Yashica FX-3, initially with speeds only up to 1/1000 sec. but later up to 1/2000 sec.
The shutter curtains are released by a cam rotating around a shaft driven by a spring. The spring has a small amount of adjustment to its tension. The position of the cam at which the second curtain is released is fixed but the position at which the first curtain is released is adjusted by altering the position of the cam follower so changing the time between the release of the two curtains. This is the only method used to adjust between the top four speeds (1/500 - 1/4000 sec.). Lower speeds use an escapement and a number of linkages to hinder the rotation of the cam and so decrease the shutter speed. The two curtains are driven by individual springs each with its own tensioner.
Curtain spring tensioners.
I had two examples of this shutter with slow top speeds and did some experimenting to find out how to adjust the speeds. Adjusting the tension on the main spring had little effect on the high speeds but had a significant effect on the slowest speeds. So any error in the slow speeds can probably be adjusted out using this method. There appears to be no adjustment of the high speeds but the high speeds can be affected by adjusting the curtain tension. If the tension on the first curtain is increased, it will travel faster and, therefore, further in the time between the release of the first and second curtains. This will make a larger slit between the two curtains and give a slower shutter speed. The opposite also happens if the tension is decreased. Of course, the tension on both curtains needs to be similarly adjusted to prevent tapering or capping. A problem with decreasing the tension is that, by slowing down the first curtain, the shutter may never fully open at the flash sync. speed and cut-off will occur when using flash. Also, if the tension is decreased too far, the curtain won’t fully complete its travel. So decreasing the tension on the curtain springs is not an ideal way of increasing the shutter speeds.
I looked for other ways of achieving an increase in the speeds and looked at ways of adjusting the time of the second curtain release. Releasing the second curtain a little earlier would have the desired effect but there’s nothing built-in to do this. The second curtain latch is tripped from a second cam that is geared to the cam on the main shaft. The second cam has a tapering slot in it through which one end of the second curtain latch lever protrudes. As the cam rotates, the lever is pushed sideways by the slot and the curtain is released. The lever was central in the slot and I thought that would allow some adjustment by making some angular adjustment (otherwise known as bending) the latch lever. I did this so that the lever was now against the side of the slot in the cam rather than the middle. A check of the fastest shutter speed showed I was now getting in excess of 1/8000 sec. Bingo! I brought the top speed back down to 1/4000 sec by increasing the curtain tension.
The following pictures show the second cam and where I adjusted the release lever. It’s not necessary to remove the parts as I’ve done here but this shows it more clearly.
To expose the second cam, remove the self timer
then the latch mechanism. Note the marks placed on the two cams to ensure realignment if they get separated.
A clearer picture of the release lever poking through the slot in the second cam. This is how it would be when cocked. Note the lever is not touching the cam so there is room to adjust it towards the outer edge of the slot so it gets activated earlier.
The point to apply a little rotation to adjust the position of the release lever in the slot of the second cam.
If the shutter is disassembled as I’ve done, ensure the latch spring is properly replaced and the self timer is properly engaged with its latch.
Latch spring in position.
Self timer pin engaged with the latch.
monopix
Cam repairer
Give me a while. I'll try and find the images and repost them.
And sorry about not being able to send me a message. Seems I unclicked the option without realising. It's back on now.
monopix
Cam repairer
Right. Just read my post to see what the images were and realised the post is out of date anyway. I've since discovered that there is a built-in way of adjusting the fast shutter speeds. I'll rewrite the post. Give me time.
monopix
Cam repairer
My original post is now updated.
philosli
Established
Does this imply the long-standing rumor that Contax S2 was made by Cosina?
monopix
Cam repairer
I've never seen an S2 with 'Made by Cosina' engraved on it and I doubt you ever will, but if you look at its construction, it's basically an updated FX-3 with some overly complicated electronics and some titanium covers.
No, Cosina didn't make the S2. Nor did they make the FX-3. Other than early ones, the FX-3 was made by Phenix in China.
Last edited:
philosli
Established
How about Nikon FM2n? Some people also suggested it's made by Cosina.
And thank you for the detailed write up. I'm amazed, though I shouldn't try this at home.
monopix
Cam repairer
Can't really comment but I would have thought very unlikely. I've only dismantled one FM2 to reclaim the shutter from it and its construction was nothing like any other Cosina made cameras I've worked on.
Cosina did make the FM10 and FE10 though. They are, I believe, based on the Cosina CT1 chassis.