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Sun 13.5 cm f3.8 telephoto from 1950's
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PostPosted: Sat Aug 26, 2017 8:39 pm    Post subject: Sun 13.5 cm f3.8 telephoto from 1950's Reply with quote
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.


Thank you!

Last edited by guardian on Mon Aug 28, 2017 4:46 pm; edited 1 time in total


PostPosted: Sat Aug 26, 2017 8:53 pm    Post subject: Reply with quote
If all glass is removed etc.Soak it in Hot soapy water.Not sure about Acetone though.Quite aggressive.


PostPosted: Sat Aug 26, 2017 9:03 pm    Post subject: Reply with quote
Eddie46 wrote:
If all glass is removed etc.Soak it in Hot soapy water.Not sure about Acetone though.Quite aggressive.


Agreed. The acetone worries me in that it is contacting the front surface of the middle element. But I saw no choice.

It is not possible to remove the middle element, or the aperture, until that distance piece comes out.

The lens is so old. It appears to be using paint as interior blackening rather than anodizing. There was sticky paint everywhere, in and out. I think it is paint gripping that distance piece . . . but I've no way to be certain. Whatever it is, so far the acetone has not touched it.

Other lenses I have worked, when you run into a distance piece during disassembly it just falls out. Not this lens. Sad


PostPosted: Sat Aug 26, 2017 9:19 pm    Post subject: Reply with quote
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?


PostPosted: Sat Aug 26, 2017 9:57 pm    Post subject: Reply with quote
Lightshow wrote:
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?


Thanks

Yes, there are two sections which can separate one from the other. There is no glass at all in the rear section just the focus helicoid and of course the mount. The rear section is detached at this point and has been set aside while I work on the front section. The balky distance piece is in the front section. Until I can get it out the middle element is trapped. And the middle element has to come out before the bad aperture can be removed.

Funny, except for the bad aperture this lens is in rather decent shape considering its age. I hope I can fix the aperture . . . well . . . actually at this point I just hope I can remove the aperture so I can work on it.


PostPosted: Sat Aug 26, 2017 10:29 pm    Post subject: Reply with quote
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.


PostPosted: Sun Aug 27, 2017 12:19 am    Post subject: Reply with quote
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?


PostPosted: Sun Aug 27, 2017 12:50 am    Post subject: Reply with quote
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...


PostPosted: Sun Aug 27, 2017 4:10 am    Post subject: Reply with quote
Eddie46 wrote:
If all glass is removed etc.Soak it in Hot soapy water.Not sure about Acetone though.Quite aggressive.


Turns out that they use Acetone as the primary mechanical cleaning agent in some optical factories, and that is after they have been vapour coated.


PostPosted: Sun Aug 27, 2017 5:02 am    Post subject: Reply with quote
Is it really worth all the effort? Even if you get it back together, it will probably not be a good lens.


PostPosted: Sun Aug 27, 2017 8:13 am    Post subject: Reply with quote
iangreenhalgh1 wrote:
Is it really worth all the effort? Even if you get it back together, it will probably not be a good lens.


Ian - tut tut! Optimism and taking on a challenge are the hallmarks of this forum's members! Our glass is always half full Smile


PostPosted: Sun Aug 27, 2017 8:35 am    Post subject: Reply with quote
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?


PostPosted: Sun Aug 27, 2017 9:08 am    Post subject: Reply with quote
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 Smile

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.


PostPosted: Sun Aug 27, 2017 4:20 pm    Post subject: Reply with quote
scsambrook wrote:
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 Smile

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.


It's actually m42 which is a key reason I purchased this lens. The ones with Exakta mount are more common but not right for me. These lenses in m42 are more difficult to locate at good price.

Anyway, after the acetone went away so did a lot of paint. It now appears I might have been full of prunes in what I wrote up thread . . . completely WRONG!! Not the first time.

The "distance piece" to which I was making reference earlier, and which was driving me nuts, now appears to be a figment of my very fanciful imagination. It looks now, with no paint, as if that "distance piece" is in reality an integral part of the overall lens body!!! Embarassed Shocked Implication is the faulty aperture does not come out through the front as I earlier wrote.

This begs the question: how did they get that middle lens element in there and the aperture?

It is gonna take more acetone to answer that, applied in a completely different place. I'm now thinking the rear portion of the front section must unscrew. I found a very thin ring of (what I believe is) glue, or thread lock. Am hoping that is the tell.

While I enjoy working on any lens, the Japanese penchant for glue and thread lock certainly does make the work far more difficult and much less enjoyable. If I do succeed in disassembling this lens and repairing it, rest assured it will go back together without glue of any sort whatsoever!!

Just this personal note regarding acetone and solvents in general. I have a high sensitivity to these things meaning it takes VERY little exposure to give me a headache. I'm not set up to work on lenses outdoors and in winter here where I live that is impractical anyway. It just so happens that weather here now is magnificent, allowing work to go forward indoors at my well-lighted work bench with two windows open nearby to provide adequate fresh air. Need to "strike while iron is hot" because these enabling conditions will not last much longer.

Finally, this heartfelt observation: I hate glue Exclamation


PostPosted: Mon Aug 28, 2017 1:16 am    Post subject: Reply with quote
Post a few pics of your current progress if you can, we might spot something you are missing.


PostPosted: Mon Aug 28, 2017 7:59 am    Post subject: Reply with quote
Lightshow wrote:
Post a few pics of your current progress if you can, we might spot something you are missing.


Thank you, Lightshow. First I must correct you: there is no progress whatsoever!

The rear portion of the front section of the lens is currently experiencing an overnight acetone soak. But I took a look before retiring and, after several hours, there is no indication whatsoever that anything is going to free up and unscrew.

My concern is that luisalegria might have fingered my problem when he mentioned a press fit. If this lens was assembled that way, with the inner element and the aperture having been retained in place with a press-fit metal retainer, I'm a goner. I've never encountered any such thing prior with any lens, but luisalegria knows much more about these things than I do and he has repaired many more lenses than myself. I really have no way of disassembling a lens that was press fit together. Application of heat, for example, is a concern because the inner glass element remains tightly trapped and could very easily crack, at which point the lens would be gone.

Of course I guess a pretty strong argument could be raised that the lens already is gone. Sad


PostPosted: Mon Aug 28, 2017 9:17 am    Post subject: Reply with quote
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!"


PostPosted: Mon Aug 28, 2017 11:26 am    Post subject: Reply with quote
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?


PostPosted: Mon Aug 28, 2017 4:40 pm    Post subject: Reply with quote
Guys a big

Thank you!

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.


PostPosted: Mon Aug 28, 2017 5:07 pm    Post subject: Reply with quote
Happy Dog Happy Cat Whoo Turtle Congrats


PostPosted: Mon Aug 28, 2017 10:03 pm    Post subject: Reply with quote
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.


PostPosted: Tue Aug 29, 2017 11:48 am    Post subject: Reply with quote
Congratulations! Glad you figured it out.


PostPosted: Tue Aug 29, 2017 12:41 pm    Post subject: Reply with quote
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.


PostPosted: Tue Aug 29, 2017 1:47 pm    Post subject: Reply with quote
guardian wrote:
...
I think that lack of operation is what caused the aperture to hang up and fail in the first place. ...


You yourself cleaned the debris/corrosion from the mounting holes. Lack of operation was not the cause of that. Smile


PostPosted: Tue Aug 29, 2017 2:20 pm    Post subject: Reply with quote
visualopsins wrote:
guardian wrote:
...
I think that lack of operation is what caused the aperture to hang up and fail in the first place. ...


You yourself cleaned the debris/corrosion from the mounting holes. Lack of operation was not the cause of that. Smile


My take is corrosion builds up slowly over a long period of time, tens of years, if there is opportunity. Early on it is not to the extent of being able to be disruptive, and if you exercise the aperture periodically it knocks off early corrosion before it can build to where things become bound up.

Storage conditions, of course, also will influence how quickly any corrosion might develop. This lens is new to me and I have no way to know how it was stored over so many years before I received it.

It was interesting that most of the aperture blade pivots were completely free and just fell out of the ring. But in the case of two or three I needed to apply a bit of pressure to free them. They were pretty well stuck.
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