Jupiter- 12 LTM, oil on iris

[lesged]

I got a Jupiter 12 LTM a few days ago, from the Ukraine via eB auction, but only yesterday noticed oil on the blades of the iris diaphragm. I've owned * a lot* of lenses in my 60 odd years hooked on photography, but never saw this on any. BTW some were very odd years, indeed.

What problems can this cause? Will it impact negatively on the quality of my photos? Will it soften the inherent sharpness of this lens? Can it creep unto elements of the lens? There is enough oil to make the significant  crescent shape on each blade when I close iris down to f11, 16 and 22.

Should I return the lens? I paid $40, with a sick FED-4 attached in lieu of a rear cap.

[melek]

What problems can this cause?
In my experience, it seems to be lubrication near the aperture assembly that has liquified and seeps onto the blades.

Will it impact negatively on the quality of my photos? Will it soften the inherent sharpness of this lens?
I suppose you might lose contrast, but truthfully, I don't know. I wouldn't expect it to affect sharpness, but you never know.

Can it creep unto elements of the lens? There is enough oil to make the significant crescent shape on each blade when I close iris down to f11, 16 and 22.
Yes, I would say that this is possible. That opening and closing the aperture blades could allow some of it to get onto the lens elements.

You could remove all of the glass, and at the very least, use some tissue to sop it up. Of course, there's probably plenty more oil in the assembly, and then you'd have to make sure the lens was collimated when reassembling.

I was going to suggest squirting some lighter fluid into it. That seems to do a decent job of removing the oil. But then that probably would get into the helicals, and before you know it you're knee deep in a major project ... all for a $40 lens.

[sandeha]

I'm only guessing here Lester, but my first thought is if you take a loupe to it what can you see, a old smear or a really wet and shiny smear?  If it's only very light, and the lens is otherwise really, really smooth and clear, then maybe it will be OK ... but, the oil is likely to be the residue of a poor rebuild and that might imply much more serious problems.

[Mike Kovacs]

Les, the J-12 that ND gave me had the same problem.  In theory it should do nothing if its only on the blades, but I found it on the optics of mine as well that are next to the diaphragm.

The Kiev survival site has detailed instructions for the brave.  Its not a difficult lens to work on, provided that you don't need to mess with the inner bayonet.

EDIT - oops sorry, I missed LTM.  Have no idea how that lens is disassembled vs a Contax mount.