I wouldn't try this at home.....normally!

[adan]

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The Setup - A couple of weeks ago I started seeing abnormal behavior from my favorite Leica M telephoto - an excellent-condition 1988 135mm f/4.0 Tele-Elmar-M. The focus seemed to become - variable - in precision. And the image quality also seemed to go to pot sometimes (excessive red-purple color fringing, rapid corner resolution drop-off). A little experimentation seemed to show that pointing the lens up or down triggered the change in behavior.

Hmmm.

The Diagnosis - I gave the lens a gentle shake, and - UH-OH! - I heard a very glassy "clink-clink, clink-clink" from inside. I was pretty sure some of the glass must have come loose and was flopping around. To narrow it down, I unscrewed the lens head (the part that is supposed to unscrew, for use on the old Visoflex pseudo-SLR viewing device). Shook that part, and got the same clink-clink. Definitely in there, not in the focusing mount or cam.

I checked the easily-accessible front and rear elements - both rock solid, even when the clinking was happening. Darn! The loose glass must be 'way inside! Sounds (literally) like an expensive (and time-wasting) trip to Leica for service.

But, just for the heck of it, tonight I gripped the very front ring of the lens (with the filter thread inside, and a slot for the lens hood to clip into outside) and gave it a gentle turn with my fingertips.

The Fix - Boom - it was happy to unscrew, bringing with it an inner tube that held the first four elements (the ones in front of the aperture mechanism). Shook that - and heard and felt "clink-clink."

AND I felt the back rim of that tube shift a bit - it was also a screw-on retaining ring, and it was loose!

Unscrewed it, and the 3rd/4th elements popped out as a cemented group in good shape. No clinking within that group. So I put it back in, replaced and tightened its rear retaining ring, and the clinking stopped. Reassembled and tightened everything with fingers alone - tight as I could. Tested the whole lens on the camera, including tiliting it between shots and shaking it. No sound, no focus issues, no poor performance. And I didn't let any dust or cat-hairs in - checked for that!

Several hundred $$S saved - and more importantly, likely several weeks/months without my 135 avoided! And just with the fingertips I was born with!

I have a couple of thoughts on this experience.

1) I've always been one who thought people who try to repair their Leica gear themselves have fools for clients.  Especially if it requires tools.

We had a case a couple of months ago on this forum about a lens just like mine that was behaving very badly. And it turned out the rear element has been replaced backwards by someone attempting a DIY fix (or, a sloppy tech).

Just for grins, I took that element out also (see image) - but was very careful to replace it the right way around.

However, I am now a little less, umm, critical of the idea of DIY Leica repairs, so long as one is very methodical and careful.

2) I do wonder how that ring, deep inside and not obviously subject to any particular stress, just decided to unscrew a mm or so (2-3 turns) all by itself, allowing the glass to wobble around. It seems to have happened almost overnight, and the lens has suffered no shocks or falls while I've had it.

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Edited December 20, 2021 by adan

[darylgo]

And Leica lenses are simply mechanical, yet I’ve learned on this lens also not to take a deep dive into repair.  Glad it worked out well for you. Mine went to DAG for reassembly and upon return the lens was and is perfect. At $400, the price hasn’t budged until recently, would repair of this lens by Leica be economically feasible?

Edited December 20, 2021 by darylgo

[farnz]

Andy, my guess is that the culprit is vibration over time. 

As an Engineer I have become aware of the human's wonderful ability to be blissfully unaware of vibration below a certain amplitude, or even slightly above that amplitude once a period of time has elapsed.  Regrettably, mechanical things often stubbornly refuse to display this ability and when they malfunction it seems to us that they have failed without reason. Complex vibration is by far the most playful as the differing frequencies can set up interference patterns that are additive or subtractive in nature and greatly increase the effect.

Like rust, vibration never sleeps.  (Just ask a seismologist.)

I'm glad you managed to de-rattle your lens.

Pete.

[adan]

Certainly could be. But when and where?

I've had this particular lens only 2 years and 2 months. It was rock solid when I acquired it. Never been in an airliner since then (notorious for high-frequency vibes). Usually kept in a padded gear bag when not in my hands.

SInce it just showed up recently and suddenly, maybe the obvious suspects were some rib-shaking musical performances I shot at the gallery this autumn. Native-American drumming for Dià de Muertos in October, and "Dark/Grunge Rock" in Nov. 

Real 110-decibel "Walls of Jericho" stuff.

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[farnz]

Good question but that's where vibration can be so playful.  We expect consistent, noticeable (to us) vibration to wind out screws and undo nuts that have no locking nut but low amplitude, periodic vibration that we don't notice, but that screws and nuts do, can undo them over time too. 

If you've taken your lens in a car then that's a potentially rich source of complex , varying vibrations and beat frequencies for example and *might* have had an effect - a motorcycle perhaps more so.

However, the point is that you've astutely and skilfully worked out what caused the rattle so you might consider judiciously applying a little Locktight or other reversible thread-locking nectar to your lens to save you having to strip the lens down in the future and cast it to the far reaches of your memory.😊

Pete.

[adan]

Brief update. I talked with a local camera repair guy with decades of experience about my "repair." And he noted that Leica went so far as to calibrate the rotation of 135 TE lens elements around the centerline of the lens (front to back)

When putting the lens together, they would put a dark red line on the side of the element (probably China Marker or similar). And then check the performance with the element installed at various angles (azimuths). And when the "best" angle/azimuth was determined, put a matching red mark on the side of the front ring it was mounted in, so that the glass would always be aligned the same way in future.

Anyway, I checked my work, and indeed the red marks were there - but not aligned. Took out the glass and replaced it with the marks aligned - and indeed achieved slightly better performance in IQ and focus calibration.

You can see the red mark faintly on the element labeled "loose lens element" in the image in post #1, at about the middle of the glass:   — 

Now it looks like  ——  when tightened into the front ring with correct alignment.

Edited January 20, 2022 by adan

[pippy]

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1 hour ago, adan said:

...When putting the lens together, they would put a dark red line on the side of the element......and then check the performance with the element installed at various angles (azimuths). And when the "best" angle/azimuth was determined, put a matching red mark on the side of the front ring it was mounted in, so that the glass would always be aligned the same way in future...

That's actually rather fascinating, Andy. So what was it which was making the lens perform differently? Was it to do with the respective calibration / orientation of the front group to the fifth element behind the diaphragm or are the front two cemented pairings able to rotate independently of each other? Or else is it to do with the contours of the ground surfaces?

I'm now quite curious about what my own early ('Red Scale') example looks like internally......but hopefully not so curious as to mess with the thing!

Philip.