A Fungus Among Us

There’s nothing quite so frustrating as discovering a lens you own has developed a bad growth of fungus on the internal elements.  Lens fungus is commonly found in older lenses.  It is indiscriminate of brand, build-quality, or price tag.  If humidity stays in your lens for too long, the dreaded fungus may appear.

I’ve spoken to a number of people who’ve shared with me their personal attempts to try to clean it off using various lens cleaners and cloths.  Let me save you some trouble:  you can’t remove fungus with standard lens cleaning solution.  Alcohol, lighter fluid, and ethanol (Vodka) don’t work either.  A combination of elbow grease and any combination of the above solutions will only result in scratches, damage to your lens coatings, and frustration.

Today, I want to share with you the simple, non-damaging way to remove fungus from your lens.  If you’re willing to put in a little bit of effort and maybe do something new, you can remove that nasty lens-ruiner and perhaps bring an old classic back to life.

Here is a list of tools and materials you’ll need to get the job done:

  1. Lens Spanner – I bought mine here for $16.50.  There is no replacement for this tool that won’t leave damage in its wake.
  2. JIS Screwdriver Set – For lenses made in Japan you’ll need a set of Japanese Industrial Standard (JIS) screwdrivers.  They look like a Philips head/cross-tip screwdriver but they are slightly different.  The tip’s pitch and depth are unique to JIS screw heads and attempting to use anything else to remove them could result in buggering it up.  I bought a good American-made set from here for about $15.00.
  3. Desk Lamp – I use two different bendy arm lights: one is an LED spotlight that provides strong, directional lighting, and the other is a multiple LED lamp with a white diffuser to provide shadow-free lighting.  IKEA is an excellent place for lamps like this.
  4. Parts Dish – I bought a $2 white plastic plate from a local home goods store.
  5. Soaking Dish – I think I paid about $3 for a little white ceramic custard dessert bowl.
  6. Tweezers – any will do.
  7. Nitrile Gloves – These will help keep your fingers from getting dried out from the fungus-killing solution, and it helps keep your glass clean while handling the lens elements.
  8. Safety Glasses – Yeah I know,  but you only get two eyes so you might as well protect them.
  9. Hydrogen Peroxide – The same stuff you get from the pharmacy aisle.
  10. Household Ammonia – I paid a few bucks at a home goods store for a gallon of this stuff.  Try to find ammonia that doesn’t have any scent added.  I’ve used scented and unscented and haven’t seen any difference in performance but it always makes me a little leery having an extra chemical in the mix when it’s being applied to sensitive lens coatings.
  11. Cotton Balls
  12. Microfiber Lens Cloth – This needs to be extremely clean.  Don’t use one you’ve carried in your pocket or camera bag.  Any dust or skin oil on the cloth will come off on the internal elements of your lens, leaving you immensely frustrated and unable to get a spotless finish.  I keep my lens restoration cloths in airtight plastic bags when I’m not using them, and replace them often.
  13. Lens Poofer – I use a $10 Giotto Rocket Air Blaster that I bought from here.
  14. Cup of Coffee, caffeinated – you’re choice of flavor.
  15. Music – I recommend Charlie Haden’s Tokyo Adagio album or Alan Broadbent’s Blue in Green.

***All photos shot with iPhone***

Alright, let’s get to it!  For this post, I bought from my local camera shop an old Konica Hexanon AR 40mm f/1.8.



At first glance you think, “It’s not that bad”…



Shine some light on it and you find it had a particularly bad case of lens fungus in the rear element group.  This is the worst place to have it because it absolutely will affect image quality.  The fungus is not on the outside of the rear element, it is between two elements inside the lens.



Time for teardown.  It’s highly likely your lens will not be the same as mine but the process is going to be very similar, especially if your lens is old, manual focus, and Japanese.  I highly recommend you use a camera (iPhone or similar) to document each step that way you have references for later when reassembling your lens.

Using my JIS screwdriver, I removed the 4 screws holding down the chrome lens mount.



With the lens mount removed, the aperture ring is now free to come away from the lens body.  To gain access to the rear lens element, I didn’t need to remove the aperture ring but I figured I might as well clean it up, too, while I’ve got all my tools out.

A big word of wisdom here: between the aperture ring and the lens body there is a tiny steel ball that has either a coil spring or leaf spring behind it that is just waiting to launch that ball across the room.  You can tell where the aperture click-ball is located by looking for the series of notches cut into the ring.  When you turn the aperture ring of a lens, the click you feel between each set point is coming from the interaction between the ball and those notches.  I suggest cupping your hand over that side of the aperture ring as you lift it away from the lens body.  In my case, there was enough grease and filth holding the ball in place that it remained safely in its hole.



With the aperture ring removed, I was able to clean up the back of the lens body.  I recommend doing at least some preliminary cleaning as you go along.  This will help keep bits o’ nasty out of other parts of the lens as you make progress dismantling things.

The lens spanner is a simple tool.  It has two steel spreader bars upon which the two spanner rods may be distanced for correct width-alignment with the ring you plan to remove.  The thumbscrews on the spanner rods provide a means to lock the tool at the required width.  This particular lens spanner has both blade and needle/pin type ends.  This lens has a pair of simple notches cut into the retaining ring.  The blade-end of the lens spanner is used to remove this type of ring.



The retainer ring is now removed, freeing the rear element from the lens.  There are several ways to remove the glass: tip the lens upside down in your hand first to see if it just drops out.  Most of the time they will.  If it doesn’t come free, you can try part-way reinstalling the retainer ring and use a blunt, non-metal object to gently rap the side of it – just enough to encourage some movement.  In the very worst case I’ve experienced, I had to flip the lens over, remove all of the front-side lens elements/groups, open the aperture blades fully and use a soft silicone spudger to press out the rear glass from inside the lens.  I’ve only ever needed to do this once so don’t get discouraged.  I just want to prepare you for that possibility by giving some pointers along the way.



In the case of this lens, the rear element simply fell out into my hand.  This is a very thin piece of glass that would take very little to break it.  I use a soft cloth or lens wipe to lay out all of the rings and glass in the order in which they’re removed.  Pay close attention to the convex/concave shape of the glass so that you have no doubts as to how they will be orientated when you go to put it all back together.  iPhone/Smartphone photos work best in my opinion.  Ok, so have a close look at this photo.  You can see that the glass that remains in the lens is the particular element with all of the fungus on it.  The first piece of glass I pulled had some traces of it but nothing like the second.  Lets get that bad boy out of there.



The construction of this lens group calls for a spacer ring between the rear most element and the inner element.  To remove it, simply tip the lens into your hand.  You may need to bump the front of the lens to get the element all the way out of its mounting.  Be careful as sometimes the inner element will come along with it.  In this case it did not.  If you ever feel more than one thing fall into your hand, FREEZE.  Set the rest of the lens down and carefully assess what is what in your hand, and in what order and orientation they were in.  Next, set down each piece onto your cloth, making sure not to allow any metal or other pieces of glass to touch the face the element(s).  Inner elements can have some very soft coatings that will scratch very easily.  A light coating scratch isn’t the end of the world but it’s best to avoid if you can prevent it.



Here we have the inner, rear element with all the fungus on it.  It pretty much covers the entire concave surface of the glass.  See the black that’s all around the edge of the glass?  Sometimes that stuff flakes off or falls off when you’re soaking the element in solution.  This blackout coating is there to reduce internal reflections.  If it starts flaking or coming off during the restoration, I recommend removing as much as will come off and re-coat it.  I’ve had good success with a black sharpie.  The edge of the glass is unpolished so the sharpie ink bonds really well to it.  I’ll usually apply it 2-3 times to make sure I get a nice blackout finish.  You can use a strong, directional light source to shine light through the middle of the lens while looking at the edges for any spots you might have missed.  An advantage of the sharpie is that it will not alter the diameter of the glass so you won’t have any trouble fitting the element back into place.





Let’s get to the good part: removing the fungus!

I have some medicine syringes that I use for measuring out the solution but it’s totally not necessary.  Our solution consists of equal parts of Hydrogen Peroxide and Ammonia.  In the past I’ve used the lid from the Ammonia bottle to measure out equal parts of each chemical.  Wear gloves and glasses if you can, and make sure you work in a well ventilated area.  The Ammonia fumes are quite strong.  For each capful of one, pour another capful of the other and you can’t go wrong.  For this small project, I only needed 5 milliliters of each for a combined volume of 10 mL.  Stir the mixture well.  Place a disposable lens wipe or something similar on the bottom of your solution dish.  This will protect the elements from being scratched by the dish while they soak.



Gently place the element into your solution.  Let it soak for at least 2 minutes.  You may see some bubbles form as the solution eats away the fungus.  After a few minutes of soaking, use a cotton ball to gently wipe away any remaining fungus.  It shouldn’t take any real pressure to do this – we’re removing the fungus chemically not mechanically.  If fungus remains on the element, just put it back in the solution for a longer soak.  I’ve had some fungus that required as much as 20 minutes to remove it all (Leica Summaron 3.5cm, if I recall correctly).



After all the fungus is gone, take the element over to a sink where you can run water over it for a bit.  Don’t rub at the lens, just let the water run directly onto it, on both sides.   Once the solution has been rinsed off, use your lens poofer to blow away all the water droplets.  With the water gone, use that sparkling clean microfiber cloth to lightly wipe the lens.  Now, inspect the lens under your lighting.  Check it from both sides and with different angles of light to be sure that all the fungus is gone and you have no dust or smudges on the glass.  If it looks good, set it aside on a clean soft microfiber cloth and cover it up to prevent any dust from settling onto it.  Repeat the cleaning process on the remaining elements.



I went ahead and removed the elements from the front of the lens too.  Why not, right?  I’ve got all my tools out, a bowl of solution ready and this will allow me to inspect the aperture as well.

Using the lens spanner, I removed the front “dress ring” to expose the front element’s retainer ring.



Next, the retainer ring was removed.



Then, in similar process to the rear elements, I removed all of the elements from the front lens group.  The glass had no fungus but there was quite a bit of dust and dirt in there.  I went ahead and gave each element a quick dip in the solution followed by a rinse, blow-down, and wiping with the microfiber cloth.


Working backwards now, I put it all back together.  The front of the lens body was cleaned and blown out, and I inspected the aperture.  It was in perfect condition.  I then reinstalled the front element group, retainer ring, and dress ring.  Look how shiny and pretty it is now!



Next, I reinstalled the rear element group.  Crystal clear, the way it should be.



Using a toothbrush with dish soap on it, I cleaned the devil out of that nasty aperture ring.  A light coating of grease (#30 from Japan) was applied to the notches to help deliver a smooth, firm clicking action.  Synthetic Moly works as well but you need to make sure it’s hi-temp grease otherwise you risk a hot summer’s day liquifying the grease causing it to drain into other parts of the lens.



I soaked the rear lens mount in Isopropyl Alcohol (91%) and gave it a good cleaning.  Each lens is a little different in how they build into the lens the aperture interface.  This Konica has the whole assembly buttoned up inside the lens mount assembly.  Some lenses are not built this way and instead are a separate collection of parts that must be removed first in order to free the mount.  Either way, they’re fairly simple consisting of a metal tab ring that is held in tension with a long coil spring(s).  If you ever have a lens that requires removing it in order to clear the lens mount, just work slow and take photos.  It ain’t rocket science in there.



Finally, all back together and looking like new again.  Total time to complete this cleaning was 2 hours, 1 minute.  That includes the extra time spent taking photos for this post.



It’s so easy even a child could do it.  Well, at least he thought he could.  My son loves to watch me work on lenses.  He is such a studier anytime I work on little projects like this.  My hopes are high that he’ll grow up into a fixer of things, if even for the pleasure of it.  My wife grabbed this shot of us with her iPhone.  Thanks  Hun, I love it!



A final shot of the mighty Konica Hexanon AR 40mm f/1.8 mounted, via an adapter, to the Sony A7RII.



I hope you found this post encouraging and helpful.  If you have any questions about any of it, please feel free to post a comment and I’ll do my best to help you out.

45 thoughts on “A Fungus Among Us

  1. Outstanding article you wrote, Tom… You could almost write a short book on lens restoration via Lulu press… I am not too sure anything like this is out there!~! Excellent job! Loved the pic of you and your son at work *smile*


  2. I love the way you write. You write the way you talk; clearly, and with humor. I love the photo of you and mini-you. That boy loves to be a part of everything technical that you do! Ha!


  3. Hey thanks Wes. I never thought I’d get into lens restoration as a side hobby but I’m glad I did. It is a relaxing and rewarding thing to do on days off. I hope to pass on to my kids this interest in tinkering. I’ve found that a lot of the mechanical principles learned from tearing down other kinds of equipment goes hand in hand with this lens business. It’s all the same stuff in the end: part A moves part B, and so forth. I’m glad you, as a fellow tinkerer, enjoyed the post.


  4. Hey Gaston. Good to hear from you my friend. That Schneider is a serious lens bud! I’d be super nervous even touching a lens like that. You have quite the collection of remarkable lenses. Have you bought an A7 series camera yet for adapting to your Leicas? When we were in Brasil I know you were using the NEX-7 with great success.




  5. How have I lived for the past 57 years and never owed a soft silicone spudger, I need one, I want one, joking aside a very good and informative write up, keep up the excellent and informative work, I am loving it.


  6. Ha! I don’t know Ian… life just doesn’t feel complete without one. If you wish to attain this spongy oneness with the universe, may I recommend a stick with a blob of clear silicone caulk applied to one end, followed by a period of reflection for 24 hours to let it dry on a piece of wax paper. Keeping the stick upright, but not touching the surface of the wax paper, will give you a nice teardrop shape with a flat end, perfect for poking many things without scratching them. 😉

    I’m super glad to hear you’re enjoying Outfor30. Readers, such as yourself, are why I keep this website going. Thanks for the encouragement to continue.

    Best to you,



  7. Congratulations for your site! Thanks for sharing your knowledge!

    The problem with fungus is that you may clean it, but it’s too hard to eradicate the spores.

    Do you know an efficient and safe way to sterilize the lens assembled?
    The only effective methods that I found which don’t damage the lens, require specialized facilities: gamma radiation and NO2 nitric-dioxide (see http://www.noxilizer.com/)

    NO2, is not efficient to sterilize grease and can damage some materials.

    Gamma radiation, may also produce free a radicals reaction which may damage some compounds.

    Maybe disassembling and separating the parts according to the adequate method to sterilize, including heat (dry or vapor) UV-C light [save to do at home].

    Also the camera body should be sterilized to prevent the spread of infection.

    What do you think about sterilization?

    Can I do something to stop the mold growing? (while I find how to sterilize the


  8. Hi El,
    Thanks for dropping by Outfor30 and for your comments.

    Regarding sterilization, this is not necessarily a requirement to prevent fungus from growing inside a lens. While a sterilized environment would prevent their growth, it is highly impractical and expensive to maintain on equipment that is regularly used. Unless a lens has been specially designed to be hermetically sealed (think NASA), any sterilization process will become null the instant that lens is brought out into the environments in which we tend to shoot. Even fixed/prime lenses exchange air with their environment. I believe thoughtful prevention is the key here. If we understand that fungus requires the following conditions to establish itself then we can make the storage for our lenses and cameras an inhospitable environment for them to live:
    1. Humidity > 60% – Desiccant or air dehydrators make it easy to maintain a humidity level between 30-50%.
    2. Food – common household dust particles are sufficient. This dust is rich in nutrients for fungi.
    3. Warmth – not all fungus requires this but the particular kind that likes the inside of our lenses does.

    If you can remove any or all of these then you will effectively break their rules for survival.

    Regarding the spread of fungus, this is where we have to maintain that inhospitable environment in our lens cabinets. A climate controlled environment, humidity less than 60%, and free of dust particles are the basics we can ensure that even if spores do find their way in their, they’ll find no means to establish and spread. The mere presence of fungus spores does not mean that they’ll be able to survive. If you have a lens with fungus already living in it, it would be a good idea to keep it separated from your other lenses until you’ve had a chance to clean it out. The method described in this article will certainly eradicate the fungus from your glass. Further cleaning of the lens body and its internal components with a 91% Isopropyl solution will sterilize them. I recommend not using Rubbing Alcohol because it is typically only 70% Isopropyl and it contains oils to help reduce the skin-drying effect of the Isopropyl. 91% Isopropyl is usually sold right next to the rubbing alcohol for about the same price.

    For your peace of mind: I have been shooting for 18+ years and have never had a clean lens of mine develop fungus. The only lenses I’ve had with fungus in them are the ones I bought deeply discounted with the intention of cleaning it. I’ve gotten some great lenses this way and paid a fraction of their going price by being willing to invest a little time and effort into their restoration. For me, it’s a practical way to buy lenses and I actually enjoy doing these restorations as a work-stress relief.




  9. Tom, hanks for your detailed answer.

    You are right, spores are in the air, but I live in a too humid and dark place.
    For that reason I want to eradicate all the fungus and spores in the optics and mechanical parts of the lens to use it in a new camera and minimize the contamination for long term storage.
    It seems that there is an accessible facility charging about $150usd for each load, I want to clean 2 mechanical camera bodies (nikon FE), 1 with electronic components an old 8mm analog video camera, and 4 lenses, that fee seems affordable if I can include everything in an sterilization load. (I have to do more research on sterilization facilities.)

    Although Hydrogen peroxide may be enough because it seems to kill spores.
    Do you know if your formula can be used to clean the mechanical parts of the lens and the camera body?
    Maybe by immersing it in an ultrasound bath (the inexpensive models at 40kHz,)
    first with your formula, then rinse with distilled water finally with Isopropyl alcohol, and dry it.

    Can vacuum packaging with silica gel inside, help to prevent fungus growth for a long term storage of cameras?
    Do you know if some components camera components can be damaged?(mechanical and electronics in DSRLs, SLRs, and video [analog and digital]) equipment?

    To end, are you ready for the next total eclipse?

    Best regards


  10. Hi El, more good questions.

    One thing to point out is that I don’t believe the 50/50 mix kills spores. Their chitinous cells are pretty hardy. Only when the spores grow out into a fungus will most solutions be effective in killing them. Sterilization methods which kill spores may also be damaging to lens and cameras; I’m not sure about that but I would do a lot of research before subjecting them to that treatment. If the process is safe, I would only deem it worth the effort if the equipment is immediately entered into vacuum bags. Because spores can be in the air anywhere you go, I wouldn’t even risk a trip home without first bagging them. Now, logic behind that process aside, is it really necessary? If you’re planning on long-term storage (5,10,20 years) then, yes, especially in your case where you live in a humid, warm climate. If you think you’ll be using the equipment once every few months, I’m not sure it’s worth the cost and hassle. That’ll be for you to decide of course.

    You definitely do not want to use this on anything electrical as it will corrode your metal contacts, the only practical way to rinse it is with electricity-conducting water. Hydrogen Peroxide is highly corrosive to most metals and is highly reactive (especially in concentration). That alone would give me cause enough to avoid using it on any metals inside the lens. Even if you’re only dipping it for a few minutes, it could be enough to cause pitting on the machined surfaces of things like your focusing helicoid, lens retainers, shutter assemblies on the camera and anything electrical. Regarding your lenses, Isopropyl Alcohol will, on the other hand, be safe to soak your metal parts in. Because it evaporates so quickly, you need only let it set out in the open for a few minutes to see all of it has left the parts you’ve cleaned with it. Like the 50/50 solution, Isopropyl does not kill spores but that doesn’t mean it is waste of time. Isopropyl will kill anything else organic in your lens that the spores might use as food to survive/grow. The spores aren’t what damage a lens, it’s the fungus it grows into that produces the enzymes which will. Take away the food source and hospitable environment and you essentially stop the spores from ever being anything more than an invisible, harmless (to the lens) spore.

    Here is how I clean the guts of my lens (not the glass): I remove all the mechanical parts, soak them (except the aperture assembly) in a dishsoap/water solution, followed by a darn good scrubbing with a soft bristle toothbrush. After this, I rinse the parts in running water. I then shake and blow them dry and then plunge them into Isopropyl alcohol to remove any remnant oils. After they’ve completely dried, I then will polish/lube/restore as necessary. The glass, I clean as prescribed in this article. As I’ve commented on before, no lens of mine that I’ve owned that was fungus-free has ever developed a fungus. I live in the South in the USA which is also hot and humid for a large portion of the year. I keep my stuff in an air-conditioned house (A/Cs dehydrate the air quite a lot), in a cabinet away from dust, with UV-emitting LEDs as lighting in the cabinet. After using a lens, I clean the front and rear glass, the body and, if the lens barrel extends, I clean as much of the barrel as I can make show and then I put it away in my cabinet. For your regular-use equipment, that should all be sufficient.

    I hope the extra info is helpful to you in your quest for cleanliness.




  11. Hi Tom,

    Thanks for posting great info on lens maintenance. I know it will come in handy.

    Speaking of the Konica Hexanon 1.8/40 (one of favorites for street photography), I was wondering if you could give any (or point me to) guidance on how to gain access to its focusing helicoid for cleaning and regreasing? Does it involve a significant disassembly or can I go in easily from the front or back, remove a couple of screws and gain the necessary access?

    Any further insight would be very much appreciated.

    – Scott


  12. Hi Scott,

    Accessing the helicoid is the easy part, it’s separating it and putting it back together correctly that can get really tricky. I’m not trying to discourage you from trying it but I do want you to be aware of the complexity. A helicoid has multiple sets of threads with multiple starting points for screwing the two parts of it together. If you’re out by even just one thread, other parts won’t line up when later you go to reassemble the lens. Additionally, you’ll have to set the infinity focus once you’ve got it all back together. Different lenses have different ways to go about doing this – some are really easy while others can require disassembly for each adjustment. I had no need to separate the helicoid for this Hexanon 40mm so I can’t advise you on whether or not it is one of the easy ones. If you decide to give it a go, let me know and I’ll try to help you out with this.




  13. Hi Tom,

    Thanks for the word of caution. I understand the risks associated with regreasing helicoids and have already had some success with Russian lenses. My hope is that I don’t have to take the helicoid apart and that regreasing the focus ring will solve the change in action in the throw.

    I suspect the best way to get at the focus ring is by disassembly from the front of the lens and was hoping you could confirm. I’ll assess whether or not I think I have enough experience to tackle the 40’s helicoid when I see how it’s assembled.



  14. Thanks Tom,
    I’ve been looking for this info for a long time I have a couple of old favourites that I’m going to try – looks as though my Pantax A* 85mm 1.4 might be saveable after all.



  15. Xavier,

    I’m so glad you’ve found this article to be of use to you. Any time I receive feedback like that, it encourages me to continue writing on this topic. Restoring lenses isn’t exactly the hottest topic online and it can be very difficult to find resources that demonstrate the tools and techniques. While I’m only a hobbyist in this, I do go to great lengths to ensure what I share is good information that considers the long-term effects of the various methods to restore a lens. My background in microscopic electronic repair has taught me a lot of things that actually carry over into this. I think the greatest tools we can have are patience and tenacity. Some of these lenses can be a real challenge to both of those but my experience has shown that with enough of each you can succeed. Check out this post to see what I mean.

    I wish you success as you endeavor to save your Pentax 85mm. Do please keep me informed on that. If you take photos and document the restoration, I’d like to feature this on OutFor30 as the first reader-submitted post. I’d like to show my readers that there are others out there who are making the effort to restore their lenses and this provides an opportunity to praise guys like yourself who will attempt it.

    All the best,

    Tom Leonard


  16. Hello Tom! I stumbled across this post by accident but it thrills me to the gills. I love my vintage lenses but the prices keep going up. I use a Sony a6000 but I’m on the cusp of buying a ff camera (I have both the a7ii and the a7Rii in my shopping cart but can’t decide! The argument is resolution vs. bank account). But back to vintage lenses. I am a girl but my dad was a tinkerer who could take virtually anything apart and put it back together. When I read your article I could actually feel my genes jumping with excitement. The prospect of salvaging a fungus-infected lens that I bought for a junkyard price ignites unspeakable joy! You make it sound utterly doable in your blog post, however some of the comments have me a bit worried. I also noticed you did not address cleaning the aperture blades, so maybe that is not necessary most of the time? I absolutely want to try this though. Thank you for your wonderful blog!


  17. Hi Lorna,
    I’m so glad you’ve found OutFor30 and have enjoyed the reading. A moderate case of fungus in a lens is an easy way to save a lot of money on an old lens. When I look on eBay for old lenses, I will specifically seek out those lenses that have it because it is usually priced well below a clean copy. I’ve saved myself hundreds of dollars on a single lens just by being willing to take care of this nuisance on my own. If you have the curiosity and patience to try it, you can save yourself some money and you may find it to be an enjoyable way to spend an afternoon. As far as the aperture goes, that’s another way to score a lens for cheap. Most aperture problems I’ve come across are due to oil on the blades causing them to stick. Many times it’s as simple as a rinse out with 90% or higher Isopropyl Alcohol or lighter fluid to restore them to their snappy operation. The hardest case I’ve had was some mild corrosion on the blades caused by water intrusion. This just required a little extra effort with some Q-tip cotton swabs and Isopropyl to tidy them up.
    If you’re interested in repairing a lens, I’d start with a cheap prime lens that you won’t be out anything if the repair goes south. I’ve bought junk lenses for under $10 that I bought just for the repair practice. Go slow, take photos of each thing you remove and you’ll be fine. In this post, I listed some basic tools – you’ll want to get those as there really is no replacement for having them. If you tackle this and get stuck, feel free to reach out and I’ll do my best to help out.


    Tom Leonard


  18. Hi Tom,

    I have been concerned about you and your family since I think I read that you moved to Florida a while back. I hope y’all are high and dry, and that your lens collection did not float away. I hope you happened to be home during that time too. My husband used to work a 32/28 shift in Africa, and I lived near the water in Louisiana so I know some of the stress and worry that goes with that lifestyle during hurricane season.

    While watching the approach of Hurricane Irma on TV this weekend I decided to practice taking apart my least valuable prime lens. It was quite an experience. I made several mistakes, one being that I was fascinated by the helicoid movement once I got that part free, and while monkeying with it it came apart in my hands. Not following your excellent instructions to freeze when something unexpected happened, I decided to clean and re-grease it (since grease had seemingly migrated all over the place anyway). This went smoothly until I got to the reassembly part. I learned firsthand that there are, exactly as you pointed out, about a half dozen different options for screwing these two parts back together. I chose about four out of six wrong before getting it right. It took a ton of time, patience, and trial and error, but I think it is back together correctly. (It works like it should.) I also had a problem getting the aperture ring to function properly. It would only give me a few clicks instead of the full range. I ended up taking the lens apart three times before getting everything to work. The downside is that it took me about 10 hours to do it, but the upside is that I understand a lot about how the inside of the lens works, and I have a clean lens now! I was so enthused by having conquered the beast, that I took apart my cherished Zuiko 100 f2. I didn’t take it all the way down, I just cleaned several of the rear elements and a couple of the front elements inside and out. It was very dusty inside. Thanks for inspiring me!

    I also bit the bullet and bought the a7R2 I had been dreaming of forever. And I found a nice copy of your favorite lens, the Minolta 35-70 f3.5 macro and wow is that ever a fun combination. You’ve been a great blessing to me!

    I do hope your home has not been devastated by the hurricane and that you and your family are alright.

    Best wishes,


  19. I have found a lot of articles and comments that fungus does permanent damage to the lens.

    What is your experience?

    The konica seems to have walked away unharmed.

    Thanks for a great article.


  20. I’m so glad that you enjoyed it! As far as permanent damage from fungus: If fungus has sat long enough on the glass, the digestive enzymes it produces from feeding can indeed permanently etch the glass. As for how long that takes, there are many variables that come into play like the type of glass/coatings, the kind of fungus, and availability of food sources. Most lenses I’ve restored that had fungus, I’ve been able to remove leaving no trace. Some really old lenses I’ve restored had a haze over the glass caused by off-gassing of the internal lubricants and I suspect that acts like a sort of buffer between the fungus and the glass, helping to protect the glass from being etched. All that to say: It really just depends and there isn’t a sure way to tell – that I’ve found – to pre-determine whether or not the fungus has caused permanent damage or not.

    All the best,

    Tom Leonard

    Liked by 1 person

  21. Thank you for that info. It gives me hope, since I have just ordered some “funghi”-lenses from Japan. I was ordering them as I was reading more about the fungus – and I bought them at the time when I was leaning towards “that’s no big deal”. Soon after I made the payment, I read how every lens with fungus is practically destroyed and no hope and …

    Now I just have to wait 3 days for the lenses, the chemicals are ready and I’ll repeat your procedure. Let’s see how it goes.

    Again, thanks for a very informative article and your reply.


  22. I am about to clean up the lens.

    Now, I was wondering about the household ammonia you use – is it 5%, 10%, 25% solution?

    Any experience with giving a bath to glued lens elements?



  23. Hi there,
    I’m happy to hear you’re taking the plunge to repair your lens. Most household ammonias are diluted to a 5-10% solution. The solution I use is 7% concentration. I have cleaned a good number of cemented glass elements and have never had an issue with separation. I should specify that their bond was in good condition with no signs of separation. If there are any signs of separation and you don’t intend on repairing this, I would not submerge the group in the solution. Instead, I would use a soaked cotton ball. Place the effected side of the lens on top of the solution-soaked cotton ball to allow it to work on the fungus. Once the fungus has been removed, you may then use water soaked cotton balls to dilute/clear away the chemical solution.

    If you have any further questions, I’ll be happy to help if I can.


    Tom Leonard


  24. Thanks Tom.

    I already started with ~25% ammonia and ~30% ph. Did it outside my house – the outgassing was visible.

    I started with the non-cemented elements.

    It cleaned them well, unfortunately I think the coating is damaged (it’s a Zeiss planar from the 90s). When the lens is dry it’s rather imperceptible, but when I breathe on it, the condensation reveals the pattern of the fungus.

    I may try soaking it for a bit longer in the solution, but I don’t think it will change much.

    I wonder what will be the impact on iq.

    Now I’ll try with the cemented elements but I won’t bath them whole, as you suggested. I’ll add enough solutions to cover the element facing bottom and a few drops into the concave element.

    I’ll let you know how it goes.

    In your post you suggested using the Japan #30 grease for lens operation. I’ve read that its good to use different grease for different elements – do you have any suggestions regarding that?

    Thank you!


  25. Thank you for the update. I’m happy to hear your making progress with it. Those fumes are indeed less than pleasant; good idea doing it outside. It sounds like you had some pretty aggressive fungus on your glass. When fungus sits for too long with a good food source available to it, their digestion enzymes are powerful enough to permanently etch the glass and remove small traces of coating. My experience has shown that – especially in front elements – this has no effect on image quality. Getting rid of a bad case of fungus even where some coating/glass damage remains still results in a noticeable improvement to image contrast. I do think it worthwhile to try a second, longer soaking just to make sure it’s not just stubborn fungus. I’ve had that be the case plenty of times. After a good ten minute soak, you can use a soaked cotton ball to gently wipe at the trouble spots. If it still doesn’t come off, you be sure it’s a case of etching which there is nothing practical you can do about.
    Regarding the #30 grease, it is all I use anymore. I use to use the #30 on the helicoid and a very thin coat of synthetic moly grease (like for cars and machinery) on the aperture ring/notches/ball but my experience with using the #30 instead has proven to work just fine. I don’t care for the smell of moly grease. #30 applied to the thoroughly cleaned and polished (metal/brass polish) helicoid parts results in buttery smooth, perfectly dampened operation. I’ve tried other high-temp synthetics and they always made things too stiff feeling, requiring two fingers gripped around it to turn instead of a single fingertip.

    Do, please, keep me updated on your progress. If you have any photos of your project you’d like to share, feel free to email them to outfor30@gmail.com. All the best to you in your endeavor to restore this classic lens!



  26. Excellent tutorial. Very well explained, detailed and illustrated. I will reproduce these steps in the lens of an Contaflex 1950 that I bought in a bazaar, is well damaged by fungi. I hope it works.
    Congratulations on the post, it’s great value!
    Ps .: The picture with your son was beautiful!


  27. Hi Mr. Leonard,
    I’ve been wanting to buy some Minolta lenses on Ebay but haven’t because most have fungus on them and I am not the take apart and fix it type of person. Have you ever repaired lenses for other people? If not, can you recommend someone or someplace that can?


  28. Hi Eric. I’m glad to hear of your interest in these excellent, old Minoltas. To answer your question regarding repairs, I do not offer any sort of repair outside of my own lenses due to not having insurance to cover such a thing and my schedule the past two years having me all over the globe without any sort of schedule. Unfortunately, I’m not able to guide you to anyone either. I got into restoring lenses because I couldn’t find anyone to do it either. I’m sorry to have only negative answers. All I can do is encourage you to consider getting a cheap lens and take a stab at repairing it yourself. After one lens, you’ll feel more confident about tackling the more expensive ones. It’s really not that bad. Just be patient with it, take lots of pictures for reference and enjoy the process.

    All the best,



  29. Thanks for your excellent explanation! I happen to have a Tokina 500mm mirror lens, which also has fungus on the large mirror; maybe also on the small one, but that cannot be seen from the ouside. (It has a Canon mount, from my analog (T90) days, and I happen to use it on a Sony A7RII now as well…)
    Do you have any additional advice about dismounting/cleaning a mirror lens?

    Regards, Jogchum


  30. Hi Jogchum,
    I’m so glad to hear the article was of some use to you. Regarding the dismantling of your reflex lens, you’ll have your main objective mirror (big donut in the rear) and then a much smaller, round mirror that faces the camera sensor/film; it is suspended in the center, closer to the front. If you have to remove this one to clean it, I suggest counting the threads before taking it off so that you can return it to its factory location. This will ensure you maintain infinity focus. These are simple lenses and shouldn’t be too much trouble at all. I do suggest a very dust-free environment. If you have trouble keeping the dust out, you can run a vacuum cleaner right near it while you’re putting it together to hopefully have somewhere for air particles to go, other than back inside the lens.
    Do please let me know how your restoration project turns out.

    All the best,



  31. Thanks for a very useful article. I tried it on an old primoplan some weeks ago – turned out the fungus had etched the glass – but it worked beautifully on a Hexanon 40mm pretty similar to yours. Pretty similar because quite a few details (shape of the retainers…) are not exactly the same. One note on the little aperture clicker ball: sure, these fly away easily, but they are also readily available for next to nothing in every possible size. For a couple of Euros, you get a little bag of 10-50 balls from various dealers over ebay. Seems their core buisiness is “soft air pistols”, whatever that is. My Hexanon 40mm has a 2mm ball, my Takumar 35mm f/3.5 has a 1,5mm ball…


  32. I have this same lens but I have another problem, the aperture blades are loose. Do you think it is possible to repair them?
    Your article is a good source to dismantle the lens, but I am not sure if it would make sense to open it and try to repair them.

    I hope you can give me an idea.

    Thanks and regards,

    The Netherlands


  33. Very informative! I bought and cleaned many cheap dirty lenses and now look forward at cleaning just the same konika 40. Love the picture with your son. Stay safe!


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