Mamiya C lens - repairable?

auntiemaryscanary

auntiemaryscanary

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I've been out today using my Mamiya C3. The 80mm lens was fine for the first 9 shots then the aperture ring went loose and now has no resistance and isn't moving the aperture.

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Does anyone have an idea about what has gone wrong or more importantly is the repairable?
 
These lenses are actually quite common even the last ones marked 'blue spot' or 'blue dot', so it may be worthwhile buying a replacement because with spare parts scarcity and labour charges there won't be much difference in the price. Also add in the waiting time for a repair to be done, if at all, if it were me I would take the replacement option.
 
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It's probably worth repairing, as long as nothing is physically broken, but not worth having it repaired as stated.
 
Nor knowing the internal construction or operation of one of these Mamiya lenses. I am purely guessing here, but one lens I did take apart out of curiosity after it became damaged and the glass cracked, the operation of the diaphragm was controlled by an outer ring on which was attached a tiny peg or pin that engaged in a drilling in the this diaphragm outer ring which made the leaves close down or open up as the case may be. If this is the same, or similar construction this 'pin' may well have broken off or dropped out so may be repairable - but at what cost?
Can I suggest that you take a sheet of white paper and hold the lens over it and gently shake the optic and see if there is any tiny rattle. The paper is there just in case there is a loose pin that drops out and isn't lost. If you get another lens you could attempt the deconstruction yourself and see if there is anything that can be done.
 
I've been looking for a replacement 80mm lens for the last couple of weeks. Not much about really. The bigger film camera shops hadn't got anything. Not much UK based on that auction site either.

I may have to consider buying a further Mamiya C camera to get the 80mm lens.

If anyone spots a likely candidate for a replacement please let me know.
 
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I cant see from the photo, but does the aperture ring have a rubber grip? If so many have a small grub screw under the rubber that works loose (common with older zooms as well) if the rings gone loose it might be something simple like that.
 
My 80mm lens has a small plastic lever on the right hand side to operate the aprerture mechanism. It bridges over the shutter setting ring and is secured in place by three screws. The two screws at the front end secure it to the ring with the engraved aperture scale. The single screw at the rear attaches to a chromed lever which emerges from the housing and operates the diaphragm mechanism.
I have had one of the front screws fall out in the past. This causes the lever to be able to rotate about the other screw and the action becomes loose and floppy. If the rear screw were to fall out, the lever would no longer be connected to the diaphragm so would cause a failure such as you describe.
If this is the case, a quick and easy fix.
 
David_Mug said:
My 80mm lens has a small plastic lever on the right hand side to operate the aprerture mechanism. It bridges over the shutter setting ring and is secured in place by three screws. The two screws at the front end secure it to the ring with the engraved aperture scale. The single screw at the rear attaches to a chromed lever which emerges from the housing and operates the diaphragm mechanism.
I have had one of the front screws fall out in the past. This causes the lever to be able to rotate about the other screw and the action becomes loose and floppy. If the rear screw were to fall out, the lever would no longer be connected to the diaphragm so would cause a failure such as you describe.
If this is the case, a quick and easy fix.
Click to expand...
Well I've had the time and the enthusiasm to have a good look at the lens.
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And it's exactly as @David_Mug suggested. The tiny grub screw has fallen out. Thank you. It's right cheered me up.

Best is it can still be used by moving the exposed metal part to set the aperture but it will be fixed.

So any suggestions where I get the right sized screw from? Would buying a cheap selection of glasses screws be an option?
 
Done.
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The screw was still too long hence scratches on the barrel. I made up a plastic washer/spacer to clear the screw off the barrel. The other 2 screws were loose as well so that wasn't helping. Tiny dot of thread lock added.

Not pretty but fully working.
 
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