Bizarre problem with Nikon El-Nikkor 50mm enlarging lens

I've had this lens for several years and have used it countless times. Today I went to install it in my enlarger and for some reason the retaining ring that secures it to the lens board didn't hold it tightly. So I decided to check it out by screwing the retaining ring onto the lens thread without the intervening lens board. I gently screwed it down until it stopped turning and then I attempted to remove it. No luck, it's stuck and I do mean stuck! I've been trying to remove it for over an hour and no luck. I have no idea how it could be that stuck. If I attempt to turn it the lens goes through its click stops and then it stops turning. Applying some force at that point does nothing. Applying lots of force similarly does nothing. I'm baffled. Does anyone have a clue how I can remove the retaining ring? I feel like I'm going to destroy the lens trying.

Hi, I was gonna say that I have no idea what would cause it to get stuck, but then I took a close look at one. Mine has about 2 or 3 active threads, and then a "run off" area at the end. So what I would suspect is that your retaining ring is thin enough that you actually went all the way off the threads on the inside. So your problem would seem to be to get the ring restarted back on the threads. Which seems like it ought to be fairly easy to do. So perhaps there's something else going on.

If I were in your shoes I'd take a strong magnifier to it in an attempt to see for sure what's going on. Step #2 (or step 1 if you don't have a magnifier) is to put on a latex rubber dishwashing glove (lightweight, preferably), and see if you can gently get the ring to get back properly onto the threads. Its possible that you have the ring cocked on sideways and it is trying to crossthread (inspection with a magnifier should show this).

The deal with the latex dishwashing glove is to give a really good grip so that you can turn the ring without needing to squeeze it hard. When you are gripping hard you may be distorting the ring such that it binds up. Such a glove can be like a miracle cure when you have stuck filters, and the like. I don't have any ideas beyond this. Good luck.

Just curious, did you store it differently? Just finished a jelly sandwich or perhaps have dirty hands when last removed? Mr. Bill is correct about the magnifier, look for dirt, cross threading. Hopefully his idea about the gloves will work. "No more dishpan hands". Please update us.

At least that is a common enlarging lens and should be easy to replace. I have two of them.
I just replaced the tie-rod ends on my car. The lock nut was tight...very tight. Even after heating with a torch, so I split it with a cutting wheel. You might consider that option.

Old_Dick said:

Just curious, did you store it differently? Just finished a jelly sandwich or perhaps have dirty hands when last removed? Mr. Bill is correct about the magnifier, look for dirt, cross threading. Hopefully his idea about the gloves will work. "No more dishpan hands". Please update us.

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I stored it the same was as always, in the original 'bubble' storage case that it came in. I'm washing my hands so often because of Covid-19 that there's no way there was any dirt (or peanut butter) on my hands when I removed the lens.

ic-racer said:

At least that is a common enlarging lens and should be easy to replace. I have two of them.
I just replaced the tie-rod ends on my car. The lock nut was tight...very tight. Even after heating with a torch, so I split it with a cutting wheel. You might consider that option.
View attachment 249806

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I hope it doesn't come to that, but I just tried with a pair of rubber gloves and no luck.

I don't see anything obvious that would suggest cross-threading. The retaining ring seems to be seated evenly all around. And if it were cross-threaded I would expect some movement. . It's like it's been welded in place!

Super frustrating, I was just about to start a printing session when this happened.

Back in my hardware (computer) days we had a saying, "FM". The second word was magic

Old_Dick said:

Back in my hardware (computer) days we had a saying, "FM". The second word was magic

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I think FUBAR is an appropriate acronym here.

I think I may need one of these. The retaining ring has two diametrically opposed slots in it that I could probably grab with this tool.

https://www.amazon.com/Andoer-Profe...EXM789SQYPF&psc=1&refRID=X4GQDNVG8EXM789SQYPF

At the risk of asking the absolutely obvious, you are turning the ring the correct way, aren't you?
Try cooling the lens a bit, before trying again.

MattKing said:

At the risk of asking the absolutely obvious, you are turning the ring the correct way, aren't you?
Try cooling the lens a bit, before trying again.

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I've tried it both ways, just to eliminate the obvious no luck in either direction.

I have a couple questions: When did the ring first get tight?

Also, can you see any male threads sticking up above the retaining ring?

And lastly, is the retaining ring bottomed out on the lens? Or is there a gap? And is it the same all around? (If there IS a gap you can test it by trying to fit things in, such as a small strip of newspaper, heavier paper, even a business card, etc.) If it's straight on the threads I would expect that the gap, if any, would be near perfectly even.

I would take a tiny screwdriver and a very small tack hammer and tap the groove of the ring a bit. Most of these damn rings are aluminum and the nice El Nikkors brass. By the way Nikon made absolutely beautiful brass 39mm lens flanges that could be mounted on a board. Allowed for easy lens change. Like a Leica screw mount lens on a camera.

I have a old POS Wollensak lens I was trying to get loose from a aluminum bodied shutter, I went so far as a Ridgid, pipe strap wrench, with the shutter clamped in a vice, no luck. Fortunately it's junk, I was trying to save the parts.

A felt or cotton Q-tip with a few microliters of liquid wrench.

SKG sells beautiful lens wrenches.

Mr Bill said:

I have a couple questions: When did the ring first get tight?

Also, can you see any male threads sticking up above the retaining ring?

And lastly, is the retaining ring bottomed out on the lens? Or is there a gap? And is it the same all around? (If there IS a gap you can test it by trying to fit things in, such as a small strip of newspaper, heavier paper, even a business card, etc.) If it's straight on the threads I would expect that the gap, if any, would be near perfectly even.

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I tightened the retaining ring today, apparently while suffering from a bout of utter stupidity. The odd thing is I didn't really even tighten it. I just gently turned it until I felt some resistance.

There are some male threads sticking up above the retaining ring.

There's a small gap between the bottom of the ring and the lens, the gap seems even all around.

Hmmm... I'll just make a few guesses, but I don't wanna make any recommendations that could make it worse.

I don't think the ring has completely come off the threads, as it has not bottomed out. (On my 50 it is undercut below the threads, such that if the ring went all the way down there I'd expect it to be loose.)

On my 50, the lens has about 2 1/2 threads on it. So if you have less than that sticking out the top this supports the idea that the threads are still partially engaged.

My best guess would be that the top part of the retaining ring had some "compressed threads" or perhaps partially damaged threads, that for some reason doesn't wanna turn backwards. (Note: compressed threads are a method sometimes used to make vibration-resistant nuts. Essentially they distort a few threads near the top of a nut such that it can be forced on, but doesn't wanna turn easily.)

I'm not gonna recommend it - your call - but if it was mine I'd probably start applying some moderate force by hand. (I might make a mark somewhere so that I'd be able to tell if it rotated at all.) The way I'd start out would be with the dishwashing gloves and use my right hand on the nut. I'd try wrapping my index finger around the retaining ring as though it were like a sort of strap wrench, and then sort of pull while squeezing down and twisting. I don't know if I'm being clear about this, but the pulling helps make the twisting force. And if I thought the threads might be galled a little lubricant per mschem might be in order.

If that didn't help I'm not sure where I'd go from there. But it would probably involve more examination with a magnifier and progressively more force, and possibly end up drilling into the retaining ring. Best of luck.

Mr Bill said:

Hmmm... I'll just make a few guesses, but I don't wanna make any recommendations that could make it worse.

I don't think the ring has completely come off the threads, as it has not bottomed out. (On my 50 it is undercut below the threads, such that if the ring went all the way down there I'd expect it to be loose.)

On my 50, the lens has about 2 1/2 threads on it. So if you have less than that sticking out the top this supports the idea that the threads are still partially engaged.

My best guess would be that the top part of the retaining ring had some "compressed threads" or perhaps partially damaged threads, that for some reason doesn't wanna turn backwards. (Note: compressed threads are a method sometimes used to make vibration-resistant nuts. Essentially they distort a few threads near the top of a nut such that it can be forced on, but doesn't wanna turn easily.)

I'm not gonna recommend it - your call - but if it was mine I'd probably start applying some moderate force by hand. (I might make a mark somewhere so that I'd be able to tell if it rotated at all.) The way I'd start out would be with the dishwashing gloves and use my right hand on the nut. I'd try wrapping my index finger around the retaining ring as though it were like a sort of strap wrench, and then sort of pull while squeezing down and twisting. I don't know if I'm being clear about this, but the pulling helps make the twisting force. And if I thought the threads might be galled a little lubricant per mschem might be in order.

If that didn't help I'm not sure where I'd go from there. But it would probably involve more examination with a magnifier and progressively more force, and possibly end up drilling into the retaining ring. Best of luck.

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Thanks for the suggestions. I've already applied plenty of force to no avail. I may take another look with a better magnifier and see if that gives me any ideas. I also ordered that tool I linked to earlier in the thread which might help, if all else fails.

This can usually be prevented by applying a thin film of petrolatum (Vaseline, for example) onto the thread before assembling.

When you grip a thin-cross-section ring such as a retaining ring or lens filter quite firmly, it temporarily flexes into an oval shape. At the two pinch points the diameter of the ring is reduced so that the ring pinches the OD of the lens thread, greatly increasing the friction between the male and female threads at these points. This is why gripping an overtightened thin threaded ring very tightly to unloosen it can make it impossible to unscrew.

Applying a tiny amount of penetrating oil to the assembled threads might help. If the OD of the ring is accessible, you might get an grip on the ring with a split compression wrench, such as sold by Japan Hobby tool. The trick is in finding one whose hole is only a few thousandths of an inch larger than the OD of the ring.

I had a similar problem when I bought a used DeVere 5108 enlarger in 2009. Someone had installed an early-model 135/5.6 EL Nikker into the DeVere threaded lens panel (39 mm Leica thread) which I wanted to remove. It behaved as though the lens had been epoxied in place. I tried seemingly everything.

I took one of my Japan Hobby Tool split compression wrenches and used it as a model to make a scaled-up version whose hole was about 0.002” larger than the OD of the chrome-plated solid-brass adapter. This is an integral part of the lens, but unscrews from the barrel on the old EL Nikkors of 135 mm and larger.

I placed the lens panel with the stuck adapter ring into a vice and used the homemade wrench. It broke loose easily without leaving any mark. A careful examination of the threads, both male and female, revealed no damage and no evidence of any adhesive. It had been overtightened which made the two threads lock together.

When two threaded metal parts are snugged together, there are microscopic “hills and valleys” on each of the two parts that can get jammed together, making it very hard to break free when disassembly is wanted. To prevent this, it’s the usual practice to always lubricate the threads with a film of grease before assembling. This makes a huge difference.

In the case of lens threads, petrolatum is a better choice. It isn’t actually grease. It’s described as parafinate, a type of wax, actually. I use this when assembling two filters or installing a slightly tight filter into the threads of a lens. This makes disassembly easier and helps prevent jams.

https://en.wikipedia.org/wiki/Petroleum_jelly

If you use a slot tool to turn the ring. Be sure to apply much greater force downward into the ring than the turning force. This is to prevent slippage, which could ruin the ring or much worse, the lens. This is the same principal as when using a screwdriver.

Put it in the freezer for a few hours and retry?

A few drops all round of WD40 often works wonders...

As things have their own minds, why not hand the lens to anyone around you, including kids, and ask them, nonchalantly, to unscrew it.

This isn’t as stupid as it may sound. There are numerous examples of people opening doors, windows, bottles, untweedling things in magical ways with a lucky twist.

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.

Darkroom since 1964. I have yet to use a retaining ring. Not needed.

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.

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.

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+1. Excellent solution!

David Lyga said:

Darkroom since 1964. I have yet to use a retaining ring. Not needed.

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