Industar-61L/D mount wobble—missing shims?

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okto

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I really like my I-61, real sleeper of a lens, especially since it was given to me, but my copy has a terrible amount of slop between the lens barrel and the mount. The threads are cut true, the mount itself does not wobble in the camera's flange, it's the fit between the mount and the focus ring/lens barrel that's loose. Allows almost a degree of wobble off axis and sometimes interferes with focusing.

It seems like there are missing shims, as this is pretty loose mechanical tolerance even for an FSU lens. Can anyone confirm the presence or absence of a shim between the mount and focus ring/mount retention ring (weirdest design, btw) on their I-61?

If it is just a loose tolerance issue, does anyone have info on where I can get shims washers in this size? I doubt my fabbing skills are up to cutting a ring that skinny out of shim stock!
 
There are no shims in the lens mount, only in the optical block - which is not your problem area. Which variation of the lens do you have - all-black I 61 L/D with printed markings? If so, they are the last ones made and that slop is probably just poor manufacturing. Best solution is to remove the end part and grease with some thick grease, which will take out most of the slop but not really eliminate it unfortunately.
 
The last ones made with the printed markings are very poorly made mechanically but stellar optically just like the earlier ones.
 
Yes, this one is a 2.8/53 И-61Л/Д domestic market model. Shame they made the mechanicals so poorly, as everyone has said the optics are nice.
I wonder if a new mount retention ring could be machined to a closer tolerance. I can't remember off the top of my head if the optical block is indexed to the flange off the lens mount or the focus helical.

Are the optical formula/mechanical specs available for this lens like it is for the Jupiter 3 and 8?
 
I have an earlier version of this lens with the same problem. The design of the mount calls for precise tolerances in several parts. I suspect a shim could be cut from thin plastic sheet but this could help or hurt. Might be simpler just to buy another lens or use grease as suggested above. Good Luck. Joe
 
Check if screws on mount are tightened. On mine I loosened them slightly to make focusing ring turning easier and touched up heads by nail polish. Looks like design allows two modes - not wobbly but stiff focusing, and a bit wobbly and easy focusing.
 
okto said:
I really like my I-61, real sleeper of a lens, especially since it was given to me, but my copy has a terrible amount of slop between the lens barrel and the mount. The threads are cut true, the mount itself does not wobble in the camera's flange, it's the fit between the mount and the focus ring/lens barrel that's loose. Allows almost a degree of wobble off axis and sometimes interferes with focusing. . . .
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I have the same lens with the printed lettering and it has exactly the same problem . . . in addition, the thread on the lens is not Leica compatible (can't use it on my IIIf). I've used it on a E-P1 with an adapter; it screws on to the adapter tightly, but is still wobbles when focusing. Really nice for portraiture wide open -- soft and evocative, but I hate handling the thing.

I read somewhere that the earlier 61, nicknamed the "panda," is better built and of equal optical quality. Yes, here is the link:

http://www.rangefinderforum.com/forums/showpost.php?p=1096445&postcount=6

And the link to the entire thread:

http://www.rangefinderforum.com/forums/showthread.php?t=76874
 
I have a several I-61 lenses and none have the wobble but I know it from other FSU optics (a J3). Just a very left field idea - would a single layer of teflon tape remove the wobble? (and the ability to focus:mad:)
 
Murray Kelly said:
I have a several I-61 lenses and none have the wobble but I know it from other FSU optics (a J3). Just a very left field idea - would a single layer of teflon tape remove the wobble? (and the ability to focus:mad:)
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Ok, I just examined the lens (haven't looked at it in a long time). Actually in the hand, turning the focus ring does not cause the lens to wobble. It is when it is screwed on to the adapter that I find the problem. So yes perhaps if I can fabricate a thin gasket out of rubber or plastic (?) to fit around the bottom of the lens it might solve the problem. Thanks. What is teflon tape?

Edit. Th lip where the gasket would fit is very narrow. If it is made too wide it will obstruct the lens movement when focusing.
 
Thanks for all the responses, y'all! I'm going to fiddle with the lens some more this evening and see if I can come up with a solution.
 
I had this same problem with a later copy; it wasn't sloppy until I removed the old grease-turned-wax, or perhaps I just didn't notice it through the rough focus. Anyway, I lessened the sloppiness by packing a bit of new grease in there, but it was still inconsistent at infinity. I eventually gave up on the copy and got a good one from a generous RFF'er that responded well to a clean and relube.
 
This problem is almost always there with the Industar 26/61 lenses, which are otherwise very good. One mitigating factor though is that when the lens moves relative to the mount it takes the RF cam with it, so the lens will be in correct focus if the camera RF says it is. Fortunately "structural grease" doesn't seem to be in the design of the other Russian lenses.

Cheers,
Dez
 
NEW DATA: I just disassembled and reassembled mine, and there's significantly less slop now. My theory is that the ring on the back of the lens with the three screws is not totally planar somehow, and I installed it in a different alignment resulting in a tighter fit. I can't say whether it will help anyone else, but it's worth a shot!
 
Might just give this a try as my 61 l/z has slop in it also, as "Dez" mentioned earlier, it seems to focus well, but it still feels shoddy. Peter
 
okto said:
I really like my I-61...
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Yes, I know your feelings. Something given is more valuable comparing to purchased one. But, just buy another one.
Cheapest lens I ever seen. In terms of price.
Try zebra one, which isn't bolt bokeh producer.
 
I both have a Zebra and a L/D version. After re-lube according mentioned link and indeed changing the position of the last ring in alignment you can get lenses without any problem.
 
btgc said:
So panda-61 is better built? I could look for it if that's true...
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Reputedly it is better built, while the LD is supposed to have better resolution . . . though both claims are disputed--and then you hear the standard refrain "FSU lenses vary in quality and that is the most important consideration." Not much help there. Seems to me like Robert @ Fotohuis is implying that both lenses are good and can be made right by repositioning the bottom ring.
 
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