As Others have said it depends what lens you want to clean.

I cleaned an older Nikkor 85mm F2 AIS which had a bit of fungus around the edge of the front element. Worked a treat and the fungus had been in there for years and was bugging me.

I also Repaired 3 Nikkor 55mm f2.8 AIS Micro lens that were getting binned from work. It was impossible to focus them as the grease had dried up found a nice tutorial on line step by step now they all work fine.

The one Other Lens that was getting binned And I am stuck Fixing is a nikkor 105mm f2.8 AIS. Again dry grease and don't have a clue with this one.

So Just because you can repair one lens does not mean they are all the same.

Did destroy a nikkor 70-200mm lens it was a newer auto focus forget which, but be warned its not for the faint hearted lens repair

Craig R

@simurg the iris blades are extremely fragile, handle with care! Disclosure: I only once took a lens apart, but, watched a pro (a friend) do it many times.

Where are you located?

Some fluids can be corrosive and remove the coatings on the lens (those coatings are fragile!). Isopropyl alcohol can remove paint and there are 2 types 70% and 99%, I believe. I think you generally want 99% or the purest you can get, but you had better get a better recommendation that what my vague memory remembers at this point. I've also seen lighter fluid used, but, can't recall if it was on optics... or maybe it was lighter fluid on optics and iso alcohol on everything else. I don't know for sure.

Someone else should chime in here or you should do some googling.

@RRRR would like to hear more about what types of lenses you have been able to work on and what your resources for info are.

My lens tech friend showed me how to de-click a Nikkor AIS lens, but, I have yet to do one myself. I have recently moved and don't have a good work bench yet.

He had to use some adhesive remover on the 6 or 8 tiny screw on the rear mount to get them loose. Yes, nikon glued their screws in place. Today loc-tite is used instead.

Another great service is in the EU, in Braunschweig, called " Classic Fototechnik".

If you can get in there and clean them yourself you'll find, the fungus has usually eaten away at the lens coatings, so depending how much you love that lens, you may not want to go there.

Cleaning a lens is a very complicated thing to do if you've never seen it done before.

Primes are simpler than zooms. There is often a central cluster of elements with a fixed front element and a rear element, if the fungus is in-between, it might not be that tough to get to and clean.

Nikkor AIS fit that description and you can forget about taking the central cluster apart yourself.

Sometimes there are 2 elements glued together and the glue yellows with age (or exposure to heat) or fungus grows from the outside to the inside on the glue.

I've had this happen on an old Leica M lens and I was able to buy just the affected front element from a dealer in the USA. A Swiss dealer told me parts for the old lenses aren't available. The US price was good so I didn't bother to look in Germany where the lens was made. The Leica LTM mount lenses are simpler than the Japanese lenses. I googled and found some pages of a book on Amazon that were viewable on the internet and it was enough to let me clean the focusing mechanism on my Leica LTM lenses, however they a re a really simple 1930's design. The front element I had replaced by a lens tech.

Specifically getting it back together so that is focuses properly is an even greater challenge than taking it apart and usually left up to a professional lens service. Your local photo shop maybe able to point you where to go or you could try some of the bigger lens services that have an internet presence like Duclos or Whitehouse A/V in California Visual Pursuit in Ohio, The photo district (many stores and techs in NYC) as wells as some good ones in the UK.

You could always buy a junk lens of the same type off ebay, take it apart and learn how it goes back together. A spanner wrench and good set of precision jewelers' screwdrivers are needed (not the junk ones for $3 at your local hardware store)

Any professional rental house or shop selling lenses has a lens tech working for them somewhere, and if you can go to them directly then you can save some money. If you ask around and see an old man in the back with a bench neatly maintained with lots of little screw drivers and bottles of fluid, take a lens to him: the old timers are usually good and may not be too pricey. I can recommend a great Inventor/Camera Repair/Lens Repair Technician in Switzerland if you want. I wouldn't recommend it if you weren't nearby, since Switzerland is not in the EU (customs & insurance issues).