How to fix a loose focus ring?

[teraflame]

Mineral spirits got into the lens somehow and now my 85 1.4's focus ring feels very loose. Nothing else went wrong, aperture and image quality is still great. How or where can I fix it?

[E. von Hoegh]

Mineral spirits got into the lens somehow and now my 85 1.4's focus ring feels very loose. Nothing else went wrong, aperture and image quality is still great. How or where can I fix it?

Send it to a competent technician. The grease (which was dissolved by the spirits) on the focussing helicoid needs to be replaced, and it will need a thorough cleaning of wherever else the mineral spirits contaminated.

[M Carter]

I would take care of this sooner rather than later - if you have thinned oil inside the lens, get it fixed before it spreads... and mineral spirits could be dissolving things like glue as well.

[PentaxBronica]

Until I read "85mm f1.4" I was all set to recommend a tube of silicone grease and a cocktail stick to spread it on the focusing helicoil.

Unless you're reasonably skilled as a mechanic I'd get it dealt with by a pro. I re-greased a 55mm 1.8 today but that was a case of repairing a fairly common lens which I'd paid very little for (the tube of grease cost almost as much as I paid for the lens!) Worth the effort though as the optics are utterly superb.

[AgX]

Silicone grease is the last thing I would like to have nearby anything I grasp. It not only creeps but is hard to remove.

I know its benefits too, I use it. But in my workshop I handle it rather like a contaminant.

[ac12]

I don't know how mineral spirits (ms) could get into the lens w/o being put there or the bottle tipped over onto the lens.

SEND IT IN for a CLA....QUICKLY.
And tell the tech what happened so he knows what to deal with.

As was mentioned the big danger is that the ms could have dissolved the grease and relocated it somewhere else in the lens where it should not be, like between the lens elements or into the aperture blades.

[David Lyga]

After I fully clean the helicoid I apply a VERY thin coating of Vaseline. It works well. Manufacturers routinely apply too much grease and, in time, you get stiff focusing. Nikons seems to be the only rational exception to this problem as they use grease sparingly. - David Lyga

[PentaxBronica]

Silicone grease is the last thing I would like to have nearby anything I grasp. It not only creeps but is hard to remove.

I know its benefits too, I use it. But in my workshop I handle it rather like a contaminant.

Well, that's you. I'm not you.

[E. von Hoegh]

OK. Everyone has their opinion, trouble is some opinions are wrong. Here's what to put on focussing helicoids - http://www.nyelubricants.com/products/damping.shtml - nothing else.
Other products may work, in varying degrees, but most have disadvantages ranging from creep to outgassing to excessive wear and all carry the disadvantage of having to do the job over again, usually involving extra work due to the aformentioned creep and so on.