RussPhoto
Member
Hello Everyone!
Got today vintage W Nikkor C 2.5 cm f/3.5 in LTM mount, all work except that the focusing wheel stuck completely and frozen at infinity (I know how to press/depress the knob at infinity) and it won't turn... Looks like the lens has been sited for decades inside of the case without use. I tried to put some 99% rubbing alcohol inside of the helicoid but still it doesn't move... Any recommendation, suggestions for a quick fix or it's required full CLA?? Thanks!
Got today vintage W Nikkor C 2.5 cm f/3.5 in LTM mount, all work except that the focusing wheel stuck completely and frozen at infinity (I know how to press/depress the knob at infinity) and it won't turn... Looks like the lens has been sited for decades inside of the case without use. I tried to put some 99% rubbing alcohol inside of the helicoid but still it doesn't move... Any recommendation, suggestions for a quick fix or it's required full CLA?? Thanks!
TenEleven
Well-known
If it's that stuck I would say a "quick" fix is out of the window. It needs a CLA.
I have serviced a couple of these lenses before and due to it being a very small 35mm lens (the LTM rangefinder standard being 51.6mm) it not only has a lens helical in there but also a translation helical that translates the 35mm focus movement of the lens into the 51.6mm that the RF cam needs. This is coupled by a tiny metal bracket through which a screw is driven inside the helical. Due to the small size all the parts are very fine, so please do not use any amount of force or stuff will break, bend or shear.
It is possible that this coupling screw has come loose (rubbing against the inner case) or the metal bracket is floating around inside the helical - and then of course no amount of solvents is going to help. There's also the chance that it has been disassembled and re-assembled wrongly (wrong helical start, etc.).
Also as a side note - please - PLEASE - do not use rubbing alcohol (IPA) on assembled lenses. Use naptha or lighter fluid, and even there one needs to be careful because you have no way of knowing or controlling where the solvents might go and cause you grief. Especially if you are not aware of the lenses internal construction. Of course IPA is fine for cleaning out the helical of dis(!)assembled lens.
Rubbing alcohol not only creeps everywhere but will absolutely dissolve the lens balsam that bonds lens elements together. Naptha is much less aggressive. I have had two very expensive lenses ruined by rubbing alcohol on my bench here and then at that stage I had to tell the customer that there is nothing that can be done. It becomes a mechanical parts lens and a basket case.
Since I am at work and can't upload my bench pictures here's a walkthrough of repairing that lens from Richard Haw (scroll down past the test images):
richardhaw.com
I have serviced a couple of these lenses before and due to it being a very small 35mm lens (the LTM rangefinder standard being 51.6mm) it not only has a lens helical in there but also a translation helical that translates the 35mm focus movement of the lens into the 51.6mm that the RF cam needs. This is coupled by a tiny metal bracket through which a screw is driven inside the helical. Due to the small size all the parts are very fine, so please do not use any amount of force or stuff will break, bend or shear.
It is possible that this coupling screw has come loose (rubbing against the inner case) or the metal bracket is floating around inside the helical - and then of course no amount of solvents is going to help. There's also the chance that it has been disassembled and re-assembled wrongly (wrong helical start, etc.).
Also as a side note - please - PLEASE - do not use rubbing alcohol (IPA) on assembled lenses. Use naptha or lighter fluid, and even there one needs to be careful because you have no way of knowing or controlling where the solvents might go and cause you grief. Especially if you are not aware of the lenses internal construction. Of course IPA is fine for cleaning out the helical of dis(!)assembled lens.
Rubbing alcohol not only creeps everywhere but will absolutely dissolve the lens balsam that bonds lens elements together. Naptha is much less aggressive. I have had two very expensive lenses ruined by rubbing alcohol on my bench here and then at that stage I had to tell the customer that there is nothing that can be done. It becomes a mechanical parts lens and a basket case.
Since I am at work and can't upload my bench pictures here's a walkthrough of repairing that lens from Richard Haw (scroll down past the test images):
Repair: W-Nikkor 3.5cm f/2.5 (LTM)
Hello, everybody! Do you know what is a “Billiken”? It’s The unofficial mascot of Osaka but with American roots, it was said that rubbing the feet will bring you good luck. His de…
richardhaw.com
Last edited:
RussPhoto
Member
Y
Yes, lighter fluid works! Thanks a lot! I'm very happy!😊 I was able to take out retaining ring on the back and separate lens block out of helicoid. After that it was half-submerged in Zippo lighter fluid for about 5 hours. Magic happened, using rubber gloves and great force focusing wheel slightly moved so I repeated the procedure for another few hours and focusing wheel turns smoothly now after applying a bit of synthetic grease. Never thought that lubricant which was used 60 or 70 years ago could be turned in form of sort of cement. Conclusion also for me if the LTM lens not in use for extended period of time never set it for infinity lock position. Thanks a lot again and Best regards!!!If it's that stuck I would say a "quick" fix is out of the window. It needs a CLA.
I have serviced a couple of these lenses before and due to it being a very small 35mm lens (the LTM rangefinder standard being 51.6mm) it not only has a lens helical in there but also a translation helical that translates the 35mm focus movement of the lens into the 51.6mm that the RF cam needs. This is coupled by a tiny metal bracket through which a screw is driven inside the helical. Due to the small size all the parts are very fine, so please do not use any amount of force or stuff will break, bend or shear.
It is possible that this coupling screw has come loose (rubbing against the inner case) or the metal bracket is floating around inside the helical - and then of course no amount of solvents is going to help. There's also the chance that it has been disassembled and re-assembled wrongly (wrong helical start, etc.).
Also as a side note - please - PLEASE - do not use rubbing alcohol (IPA) on assembled lenses. Use naptha or lighter fluid, and even there one needs to be careful because you have no way of knowing or controlling where the solvents might go and cause you grief. Especially if you are not aware of the lenses internal construction. Of course IPA is fine for cleaning out the helical of dis(!)assembled lens.
Rubbing alcohol not only creeps everywhere but will absolutely dissolve the lens balsam that bonds lens elements together. Naptha is much less aggressive. I have had two very expensive lenses ruined by rubbing alcohol on my bench here and then at that stage I had to tell the customer that there is nothing that can be done. It becomes a mechanical parts lens and a basket case.
Since I am at work and can't upload my bench pictures here's a walkthrough of repairing that lens from Richard Haw (scroll down past the test images):
Repair: W-Nikkor 3.5cm f/2.5 (LTM)
Hello, everybody! Do you know what is a “Billiken”? It’s The unofficial mascot of Osaka but with American roots, it was said that rubbing the feet will bring you good luck. His de…
