[vladimiroltean]

No use I'm afraid: inhaling it has the same effect, as far as I'm concerned.

[mer]

these suggestion seem mad to me.

I just use very high quality microfiber cloth like calocloth or others and air blower. Some dust is ok it wont really affect the quality , oil ( grease ) is not ok , good quality microfiber cloth should do it. IF NOT , I would mix 50%ethanol or isopropyl with 50% distilled water if oil persists. It's ok if you do it once and fast and dont use a lot promise you smcoatings gonna be ok .

[vladimiroltean]

Hi mer, I'm not sure that "mad" is the right word, after all everyone uses only what works for theirselves. In my experience, either ethanol or isopropanol leave some residue behind when drying, and so does distilled water applied afterwards (oddly?) But I hope methanol does a better job.

[Just1MoreDave]

It is possible that the fungus etched the lens coatings. So what you see is not a spot you can't remove, it's the spot where the coatings are missing.

[ripit]

Hi mer, I'm not sure that "mad" is the right word, after all everyone uses only what works for himself. In my experience, either ethanol or isopropanol leave some residue behind when drying, and so does distilled water applied afterwards (oddly?) But I hope methanol does a better job.

It could be there is some sort of contaminant in what you are using, or I'm thinking in many cases there was still something on the lens that's just not very visible, and the water or alcohol is just bringing it up into a spot. I think the best bet is you use something that is going to absorb and or capture everything (micro fiber), liquid or solid, and wipe off the lens while with a dry section while the lens is still wet so that everything is carried away.
I also agree that using a good micro fiber cloth is important but I don't think price really determines that. I have some ebay ones I got that looked identical (like they came out of the same factory) as the expensive 3m lens cloths I have and they worked just as well. I have to wonder if some of these shipped direct from china items are identical to branded ones and come out of the same Chinese factory. I recently got some wall-e toys from a Chinese ebay seller very cheap and they appear to be Disney store merchandise intended for the European marked (I have bought plenty of knockoff stuff ans these look real including packaging).

[borno]

Hi mer, I'm not sure that "mad" is the right word, after all everyone uses only what works for himself. In my experience, either ethanol or isopropanol leave some residue behind when drying, and so does distilled water applied afterwards (oddly?) But I hope methanol does a better job.

I use lab grade Methanol on lenses and sensors when needed and it works very well for me. I think Eclipse is just methanol from what I have heard. I have found the cleaning fluid you can get through the mail because it is "safe" to ship (non flammable) are crap. I don't have a camera store nearby to buy eclipse fluid and was lucky enough to get the methanol when we were cleaning out some chemicals we didn't need in the lab at work.

[vladimiroltean]

Another update: I chose Zippo lighter fluid over Eclipse methanol, purely because I could get the former in a much larger quantity, and much cheaper. It seems it has done the job too (I left maybe a dust speck or two inside, as for the first job ). Now I'm having problems assembling the last part, the lens mount, because I have to reset the infinity focus (what a fool have I been that I disassembled that part). I really have no idea how to systematically adjust the focus, other than gross trial and error. Maybe someone with the same lens could tell me what is the distance between the edge of the focus ring and the lip of the barrel, when focused at infinity and at minimum distance? Thanks a lot.