How much should I dilute hydrogen peroxide to remove lens fungus?

[Certain Exposures]

Hello there,

What strength hydrogen peroxide should you use to soak the lens element before scrubbing to remove the fungus? Do you need to dilute the hydrogen peroxide in water first? How long should you soak it on average?

I've watched a couple videos but neither of them elaborated on those points. Do you have any recommendations based on your experience?

I'd prefer to avoid using ammonia.

[Havoc]

I use a mixture of:
- 5ml ammonia as found in the diy (13% if I remember, it is some time I did this)
- 5ml of 30% peroxyde
- rest distilled water to 100ml

I soak it in 10-20 seconds to begin with. You will have a lot of bubbles so stir around a bit. Then take out, clean in distilled water, dry and check. Repeat if needed. But again, it is some time since I last did this.

And this is only soaking the lens elements in it, never the whole lens.

[domaz]

It may work or it may not in my experience. Don't expect miracles but if the fungus hasn't been on the lens long enough to etch it, it will help

[Certain Exposures]

I use a mixture of:
- 5ml ammonia as found in the diy (13% if I remember, it is some time I did this)
- 5ml of 30% peroxyde
- rest distilled water to 100ml

I soak it in 10-20 seconds to begin with. You will have a lot of bubbles so stir around a bit. Then take out, clean in distilled water, dry and check. Repeat if needed. But again, it is some time since I last did this.

And this is only soaking the lens elements in it, never the whole lens.

Thanks - your signature made me wonder though...

It may work or it may not in my experience. Don't expect miracles but if the fungus hasn't been on the lens long enough to etch it, it will help

Thanks.

Unfortunately, I think someone used some sort of sealant on the retaining rings. They're shut tight. I'll have to figure out how to get them apart without damaging anything.

[Kino]

Place a drop or two of 95% alcohol on the retaining ring threads and give it a few minutes to penetrate. This sometimes helps loosen the rings...

[Certain Exposures]

Place a drop or two of 95% alcohol on the retaining ring threads and give it a few minutes to penetrate. This sometimes helps loosen the rings...

Thank you. I will try that.

[Certain Exposures]

Place a drop or two of 95% alcohol on the retaining ring threads and give it a few minutes to penetrate. This sometimes helps loosen the rings...

The good news:

I used a generous helping of 70% alcohol and it worked perfectly. By "generous" I mean that I put enough around the ring to penetrate the seal between the lens retaining ring and the lens thread but not so much that I got any on the lens element or let any pool up much between the cracks.

I got the offending inner rear element out, soaked it in some solution, dried it, buffed it, and replaced it in the housing. I recorded video of my first failed attempt to open up the lens and my second successful attempt to open it up. You can see it makes a nice difference.

The bad news:

Neither the inner or outer rear lens elements "fit" neatly back into the rear lens element housing. They seemed unleveled to me. I used gentle pressure (or what I thought was gentle) to coax the rear outer element back into position evenly but I ended up pressing too hard and cracking the glass slightly on the outer edge.

So now I have two questions.

1. How noticeable do you think this defect will be in my photos? I do not own a lens board or camera to test this lens out yet:


P.s. the glass doesn't look great here but it's much cleaner than what I got thanks to this learning experience.

2. How exactly are you supposed to get the lens elements back in evenly once they come out? Trial and error? Or was it never supposed to come out in the first place? Gently twisting and applying pressure didn't work.

[Havoc]

Thanks - your signature made me wonder though...

Thanks.

Unfortunately, I think someone used some sort of sealant on the retaining rings. They're shut tight. I'll have to figure out how to get them apart without damaging anything.

Sorry for that It has been some time since I done that. I did 3 lenses like that and with the 135/2.8 orestegor I had a damaged coating. Now I have no way to know if that is due to the mixture or due to the fungus eating it. The mamiya lenses however came out clear. But as you also found out, taking them apart is often the hard part (the 150/3.5 was very difficult). So I'm less inclined to but lenses with fungus these days. I have one other to do and I can't even find where to start taking it apart.

I don't think the little chip completely at the side will bother you much. There is a possibility when direct sun hits it, to be checked I guess. But yes, taking apart and putting back together is the hardest.

The elements should slide in if you put them in dead straight. Cleaning the barrel very well will help. Microfiber cloth, alcohol swab etc. Same with the outside of the elements but there you need to be very careful and I would not use alcohol on any painted edge.

[Certain Exposures]

Sorry for that It has been some time since I done that. I did 3 lenses like that and with the 135/2.8 orestegor I had a damaged coating. Now I have no way to know if that is due to the mixture or due to the fungus eating it. The mamiya lenses however came out clear. But as you also found out, taking them apart is often the hard part (the 150/3.5 was very difficult). So I'm less inclined to but lenses with fungus these days. I have one other to do and I can't even find where to start taking it apart.

I don't think the little chip completely at the side will bother you much. There is a possibility when direct sun hits it, to be checked I guess. But yes, taking apart and putting back together is the hardest.

The elements should slide in if you put them in dead straight. Cleaning the barrel very well will help. Microfiber cloth, alcohol swab etc. Same with the outside of the elements but there you need to be very careful and I would not use alcohol on any painted edge.

The part I bolded is a really important clarification! It would be worth adding that as a warning before your suggestion so that no one damages something by accident.

Unfortunately, the elements would not slide in even though I put them in dead straight. I will try cleaning the barrel.

[Havoc]

Well that is a risk when you touch a coated lens with any chemical.