Bizarre problem with Nikon El-Nikkor 50mm enlarging lens

jtk · Jul 7, 2020

Rick Jones said:
At this point, if it were my lens, I would use my dremel tool to cut through the retaining ring to a point just short of the lens thread and then split the ring. I would be willing to sacrifice the ring in favor of hopefully saving the lens threads.

Yes. I'd avoid any sort of penetrating juice because it will work it's way into the lens. HEATING might work (might expand the ring) but I'd be careful to avoid more than 150 deg (the temp in a hot car when ambient is 100). If it was mine I'd put it under a hot fluorescent light bulb (if you still have one) and keep it there for several hours.

jtk · Jul 7, 2020

David Lyga said:
Darkroom since 1964. I have yet to use a retaining ring. Not needed.

Modern times.

David Lyga · Jul 7, 2020

DWThomas said:
??? Suppose your lens board bore isn't threaded? (Don't think Fleer's Double Bubble gum is made anymore! )

David Lyga · Jul 7, 2020

Honestly never thought about that.

reddesert · Jul 7, 2020

There are 2-1/2 threads sticking out above the retaining ring. If it doesn't come off with a tiny bit of lubricant, you could get an M39 flange, mount that to a lensboard, and screw the lens into the flange, leaving the stuck retaining ring in place.

NB23 · Jul 7, 2020

Sal Santamaura said:
I see multiple suggestions to cool the assembly. In my experience, that's backwards. Gently heat it, perhaps using a hair dryer on low. Then give the rubber-gloved-firm-twisting approach another try.

Heat causes metal to expand while Cold will contract.
In theory, Cold should work better in this case.

Even in garages, blasting cold air onto seized mechanical parts would work better than blasting a flame. It’s just that cold flames machines don’t exist...

Vincent Peri · Jul 7, 2020

It's my experience that cold does indeed work better than heat. With heat, you risk making lens lubricants run into places they don't belong.

Sal Santamaura · Jul 7, 2020

Sal Santamaura said:
I see multiple suggestions to cool the assembly. In my experience, that's backwards...

NB23 said:
Heat causes metal to expand while Cold will contract.
In theory, Cold should work better in this case...

In practice, the jam nut will expand much more than the lens threads will.

NB23 said:
...Even in garages, blasting cold air onto seized mechanical parts would work better than blasting a flame...

No flame blasting was suggested:

Sal Santamaura said:
...Gently heat it, perhaps using a hair dryer on low...

It would be interesting to see what happens if the OP tries my approach.

logan2z · Jul 7, 2020

Thanks for the continued flood of suggestions.

I thought about using a Dremel to cut the retaining ring off but I have a feeling that won't end well - I'll likely end up damaging the lens beyond repair.

I tried cold yesterday but that didn't seem to help. I might give Sal's hair dryer suggestion a try next.

I've got that lens tool arriving on Thursday that I'll try if I don't have any luck before then.

So crazy...

Old_Dick · Jul 7, 2020

Filter wrench? Vise-grip? 3 year old kid?

jtk · Jul 8, 2020

jtk said:
Yes. I'd avoid any sort of penetrating juice because it will work it's way into the lens. HEATING might work (might expand the ring) but I'd be careful to avoid more than 150 deg (the temp in a hot car when ambient is 100). If it was mine I'd put it under a hot fluorescent light bulb (if you still have one) and keep it there for several hours.

Didn't mean "fluorescent." Meant to suggest a conventional light bulb (old fashioned kind). That or, if you have hot weather, just keeping it in a hot car for a day.

logan2z · Jul 11, 2020

Well, I finally managed to remove the retaining ring. I used the lens repair tool I bought, with a little help from some heat from a hair dryer, and it came off. The threads on the lens seem fine so I think I'm out of the woods.

Thanks to everyone who offered helpful suggestions.

I bought a Schneider Componon-S as a backup in case I ever have an issue with the El-Nikkor again. I've wanted to try one for a while anyway and this was a convenient excuse

Sal Santamaura · Jul 11, 2020

logan2z said:
Well, I finally managed to remove the retaining ring. I used the lens repair tool I bought, with a little help from some heat from a hair dryer, and it came off. The threads on the lens seem fine so I think I'm out of the woods...

logan2z said:
...Thanks to everyone who offered helpful suggestions...

You're most welcome.

Bizarre problem with Nikon El-Nikkor 50mm enlarging lens

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