Threaded retaining ring

What ho one and all,

New to this forum and new to fixing photographic things.

Just taken delivery of some repair equipment, including a set of rubber lens wrenches. Have a 'disposable' old Pentax zoom lens to play with as a learning exercise.

Used the correct sized rubber wrench to undo the front element retaining ring and it started turning but for whatever reason, now appears to have jammed. The lens is loose but I can neither tighten nor undo the ring. Not possible to have cross threaded as I did not manage to remove the ring.

Is there a secret to either removing or tightening in this situation?

Many thanks and toodle pip.

Welcome to Photrio.
I'm going to move this to the camera repair sub-forum, because that seems appropriate, and your query may be more likely to be responded to there.

It can happen that a ring turns easily and then gets stuck. There may be a small irregularity in the thread.

It is unlikely that the ring will jam when unscrewing as it is already in the thread. This sometimes happens when screwing it in.

Putting a small amount of light oil or WD-40 in the thread and allowing it to work for a while can help to loosen the blockage.

First, thanks for moving to an appropriate section. I did look for a 'Lens' forum, but did not see one.

Will try a bit of either WD or I do have a silicone spray and would just use a small drop. Agreed, it is easy to mis-align the threads on replacing but that was not the case this time.

I like taking things apart and see how they work. I do that on my 21 y/o car; now absolutely fascinated by all the mechanisms within a lens and mechanical camera, so thought I would give it go.

Rekusu said:

Will try a bit of either WD or I do have a silicone spray and would just use a small drop. Agreed, it is easy to mis-align the threads on replacing but that was not the case this time.

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It is important to give the matter (WD-40) time, I would let it take effect for at least an hour, I am always too impatient.

Rekusu said:

I like taking things apart and see how they work. I do that on my 21 y/o car; now absolutely fascinated by all the mechanisms within a lens and mechanical camera, so thought I would give it go.

Click to expand...

Welcome here, never give up!

Yes, a small irregularity or some dirt in the threads could be an issue. Some oil. A dental pick run through the threads. Of course now that you are jammed , if it is an object is is probably unreachable inside the threads.

Another possible issue is that there is slop in the threading and pressure while unscrewing can make the ring get skewed and jammed. Try very light pressure. Sometimes a little double stick tape on the ring can allow for a good enough grip with light enough pressure to unjam it. Try applying very even steady pressure around the circumference to see if you can get the threads to unjam by pressing all around to the back of outer threading. And back and forth. Sometimes going backwards is needed to reseat everything smoothly.

Put it in a plastic bag then in the freezer for a few hours. The problem is condensation if you expose the cold lens to warm air.

If nothing works, and the ring has some width, consider drilling two holes for a spanner wrench. Of course depends on the value of the lens.

Be prepared for a few cadavers along the way of learning these repairs.

Thanks for the replies.
Yes, I have considered a couple of holes for a spanner wrench. However, a bit of success with the WD. With sufficient pressure, I have managed to screw it in, so I know it is not cross-threaded. It will turn around 2 revs before tightening up again. Am assuming that a previous owner had a filter issue and the thread is slightly knackered. Will inspect closely and figure out some way to 'clean' or smooth the thread.

All part of the learning curve. Currently scouring eBay for a cheap mechanical camera to play around with, but all the 'spare or repair' decent cameras are price at a level beyond what a non-working camera should be. Probably have to go with a Zenit or Practica to play with.

Pentax K1000 is a nice learner camera.

The tip of an X-Acto knife blade can be used to clean out an slightly reshape fine threads.

Update: I have been attempting to 'clear' the thread on the lens barrel but no such luck. Some dental tools, scalpel, but the retainer ring still gets jammed after a couple of revolutions. Am unable to see the exact problem, apart from the obvious, a damaged thread and unless a thread is about 99% perfect, it will jam.

A Google search does find solutions but they all assume the filter thread is damaged (it is) and the filter is not in place. Nothing about a lens retainer ring.

I see the thread pitch is most likely 0.75mm but I don't have any small bolts with the pitch.

Apart from 'breaking' the ring, is there a solution?

For about 40 or 50 quid, you can get a lens-ring vice:


or


I haven't needed one, so can't say how much help it is.

Thanks for the links. Must admit, the combined Neewer tool looks interesting. Don't think I need it yet, as I am a fully paid up rookie at this business.
Also, seems to me that the vise is to restore bent thread, not crossed or thread damage.

It is only a 'playing' lens so not breaking my heart, but would be nice to open it without excess damage.

Have you tried double stick tape on the ring? If you are using a rubber stopper or such, the tape can give you enough grab without needing to apply too much down force.

And then back and forth, with some oil in the threads. Just keep trying to get it out, back off, get a 'running start' and do it again and again. It can be only a very small each time for a while until the flaw is broken through or passed by, but it can work.

Good idea; I'll give that a try. Hope I have not damaged the threads too much in trying to correct the problem.

No luck to date, the ring still jams at around 1.25 revolutions from full 'lockdown.' Have been trying to adjust the visible section of the filter thread but am most likely, making things worse.

It is no big deal as the lens was purchased as a 'let's give it a try' learning experience. But I also see that however this lens comes apart, it will not be that way for another lens. So I guess the 'learning experience' is about getting a general idea of how things work.

Thread gauges can be useful as sort of a shaping tool. Can almost use it as a scraper to clean out threads. Makes sense to call it a day on this lens but down the road a set of gauges could be useful.

In the days when I was working, I made models and props for TV advertisements; basically, a jock of all trades, master of none. Yes, I do have a thread gauge set and have been trying to correct the thread, but to no avail. I also have so many other small tools, screwdrivers, dental picks, etc.

Regarding this lens, I followed the drill tow opposing holes suggestion to get more leverage with the lens spanner. Still a no-go. Decided to therefore, to force the retaining ring off but cutting through it. But again, it will not budge. Impossible to see, but I suspect that rather than being a simple male ring, it is likely L shaped so that the element locates centrally within. If this is the case, then part of the rings is not visible and still intact, hence causing the jamming and also preventing me from pinging it off.

As the lens is probably now a goner, will continue to play with it for the learning experience. I do suspect that if the front element is removed, there are some screws below that would allow the removal of the front barrel and lens hood. At the moment, I can not see any way to remove the hood.

I'll keep playing!

A picture sure would help.