Sun 13.5 cm f3.8 telephoto from 1950's

[guardian]

I brought in an old Sun telephoto. I liked the lens for its own sake but also more particularly because it has the m42 mount. Think it might be from the 1950's.



More photos here:

Click here to see on Ebay then click see original listing

Upon its arrival I discovered the lens is not in good condition. The aperture needs work. Otherwise, actually, it really is a nice specimen. Decided to try to repair the aperture.

Need help. Rear lens group removed pretty easily and the front element came out with manageable difficulty following application of lots of solvent.

The aperture comes out through the front. There is a distance piece and then the middle element and then the aperture. The distance piece will not budge. It is not screwed in, but I think paint might be gripping it.

So far I have filled the entire front cavity with solvent (acetone). Distance piece still will not move . . not even a little.

If anyone has ever taken one of these lenses completely apart your counsel would be invaluable.

[Eddie46]

If all glass is removed etc.Soak it in Hot soapy water.Not sure about Acetone though.Quite aggressive.

[guardian]

[Lightshow]

If acetone doesn't touch it, try isopropyl alcohol, then if that doesn't touch it, the only other thing I can think of is mineral spirits/paint thinner/varsol.
I don't have any experience with this lens, so I won't be of much help, does the section in front of the focus ring unscrew from the rear section?

[guardian]

[luisalegria]

I have one of these, but I have not had a problem with it so I can't really help. The spacer you mention could well be press-fitted. Pictures of the inside might help.

All sorts of things can be tried. Rubber wrench (a rubber cylinder) is one option, maybe.

[Lloydy]

warm the lens body with a hair drier until it's just hot enough to hold, pour ice cold water on the spacer ring, and it might shrink enough to come out?

[visualopsins]

Neat Wintergreen oil penetrates. The secret ingredient in Marvel Mystery Oil product. Not WD40 (WD = water dispersant.). Local pharmacist probably has some behind the counter...

[Teemō]

[iangreenhalgh1]

Is it really worth all the effort? Even if you get it back together, it will probably not be a good lens.

[scsambrook]

[iangreenhalgh1]

But one should pick one's battles, otherwise you end up losing and gaining little or nothing.

I could understand persevering with a Zeiss or Schneider, but a Sun?

[scsambrook]

Well, Ian, maybe it's the only battle Guardian has, or wants, to fight. If he "loses", what's he lost? And why not persevere with a Sun lens? It's an example of what the still immature Japanese photo-optical industry was turning out in the mid 1950s and - to anyone with an interest in the early evolution of technological businesses it's far more intriguing than anything from Zeiss or Schneider of the same period. But then, I'm one of oddballs who is interested in who made it, how they made it, and why they made it

And Guardian's lens looks like it's styled after the contemporary Leitz 90 and 135 lenses - which prompts me to ask him if it is indeed in Leica rangefinder mount.

[guardian]

[Lightshow]

Post a few pics of your current progress if you can, we might spot something you are missing.

[guardian]

[scsambrook]

Guardian writes
"Of course I guess a pretty strong argument could be raised that the lens already is gone"

Well, perhaps that's so, but unless the iris is stuck at a very small aperture, it should have at least some photographic capabilities, as long as the optics are in good condition. "Always Look On The Bright Side Of Life!"

[Eddie46]

Just a thought,does the lens by any chance come apart at the lower end of the recalcitrant bushing, as in screws apart into two sections? I see a grub screw in the image,what does that hold in place?

[guardian]

Guys a big



to all who tried to help out. It was very generous of you.

To Klaus:

Thank you for your patience. Should you want now to move this thread over to the repairs board . . . fine by me. If not . . . . also fine by me. I appreciate the exposure you allowed here. I have changed the title so others needing help with this lens, in future, will be able to find this thread wherever it might be.

I will do some writing, either now or later today, in effort to help out others who might face, with this lens, the dilemma I faced.

For the moment suffice it to say my lens is now completely disassembled, making way finally for repair to the aperture. I actually gave up on the lens. Then decided to try one last, desperate, measure, my monkey wrench. Monkey wrench is also called a Stillson wrench or a plumber's wrench. With the Stillson applied to the rear portion of the lens's front section, and gripping tightly the serrated ring at the very front of that section, lo and behold it gave way and unscrewed, freeing the aperture and allowing its removal.

I had no advance inkling whatsoever this would happen, and I certainly never would have guessed the location of the joint which unscrewed. It is located immediately behind the serrated front ring.

The lens is nicely made and highly serviceable . . but only for those who know in advance how it is put together . . . which I did not.

[visualopsins]

[luisalegria]

Good on you!

"but only for those who know in advance how it is put together . . ."

All of these things are journeys of exploration, off into the wilderness.

[uddhava]

Congratulations! Glad you figured it out.

[guardian]

Thank you for the very kind reactions. I will be commenting here further, piecemeal. Some Q & A follows:

Q: You said you gripped the lens with a Stillson wrench. Those have aggressively sharp, serrated, large steel jaws. Did this not mar and destroy the outer body of your aluminum lens?

A: I made multiple folds in a large linen handkerchief, then used those layers of cloth to protect the lens body from the wrench's steel jaws. There is no visible damage to the lens body. But the Stillson allowed me to grip the lens much more tightly than was possible during multiple, failed, earlier efforts when I used only my hands.

Q: What can you say about the aperture? Was there permanent damage?

A: The aperture of this lens has sixteen steel blades. The pivots at either end of each blade are brass. The blades are asymmetrical, pivot locations being a bit different as between one end and the other.

In several instances blade pivots were hanging up, they were stuck, in the holes in the brass ring into which each blade pivot fits. I cleaned all sixteen holes in that ring with a slightly under size drill to remove corrosion or burrs or anything else which might have been inhibiting necessary blade pivot rotation in those holes.

But there was no detectable permanent damage to the aperture blades. Upon reassembly the aperture operated in a 100% nominal fashion, giving no indication whatsoever of its prior dysfunction.

It is a rather old lens, older than most of my other lenses. My guess is that it sat unused for many, many years during which time the aperture was never exercised. I think that lack of operation is what caused the aperture to hang up and fail in the first place.

Q: With the aperture having been serviced, were there any issues reassembling the lens?

A: None whatsoever. I cleaned up the elements a bit and just put everything back together. It is not a complicated or particularly challenging lens once you know where and how it comes apart.

Q: Any issues with the rear portion of the lens?

A: Focus is a bit stiff, something which could be solved with a re-lube of the helical. I have no plans to service the helical because I can live easily with the minor stiffness. The focus ring of this lens rotates through roughly 300 degrees end to end which is a desirable feature IMO.

[visualopsins]

[guardian]