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11-04-2021, 03:51 AM   #1
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Lens elements still look dusty after cleaning

Hi everyone,

I recently disassembled a fungus and dust infected S-M-C Takumar 135mm f/3.5. Must of the crud inside looked like dust, with only a hint of fungus. I cleaned the lens elements in soap water, let them in the soap water over night and then used ethanol and lens cleaning tissue. Below is a photo of how they came out. It looks like there is a lot of dust left, but I'm not able to remove it.

Before I turn to hydrogen peroxide (and fear for the coating) I wanted to ask you guys what this might be. Is it fungus that has eaten into the coating? Do you have any recommendations on how to clean it by less aggressive means?

I read about Pond's Cold Cream. Does anyone know where to get this (or an alternative product) in Germany? DM and Müller don't have it. Yes it's available from Amazon but I prefer biking to the next drugstore (Drogerie, you know what I mean )

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Last edited by trilean; 11-04-2021 at 05:19 AM.
11-04-2021, 04:04 AM   #2
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Is that particular element the only one affected? Is it the exterior or interior surface that has this look? Can you feel it with your finger?
11-04-2021, 04:12 AM   #3
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All elements are affected to some degree, however this one (2nd from front) is the most affected. It's a four-element lens and the order is 2-1-3-4 from worst to best. Also I can't feel any bumps or rough spots in the glass.

The three front elements are screwed together, so there's no real interior/exterior surface here. However it looks as if the front-facing side is more affected.
11-04-2021, 05:04 AM   #4
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Is it still covered by the warranty period? Can it be sent to Ricoh for repair?

11-04-2021, 05:07 AM - 1 Like   #5
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QuoteOriginally posted by biz-engineer Quote
Is it still covered by the warranty period? Can it be sent to Ricoh for repair?
It’s a 50 year old lens.
11-04-2021, 05:18 AM - 1 Like   #6
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QuoteOriginally posted by boriscleto Quote
It’s a 50 year old lens.
Extended warranty then… lol.

---------- Post added 11-04-21 at 08:20 AM ----------

QuoteOriginally posted by trilean Quote
All elements are affected to some degree, however this one (2nd from front) is the most affected. It's a four-element lens and the order is 2-1-3-4 from worst to best. Also I can't feel any bumps or rough spots in the glass.

The three front elements are screwed together, so there's no real interior/exterior surface here. However it looks as if the front-facing side is more affected.
It looks like an old sigma af 400 I had that had fungus that after cleaning had coating damage. Not easy to tell from photos.
11-04-2021, 05:26 AM - 2 Likes   #7
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I believe it is the coating failing.

As to cold cream- Pond's or other brand:
"Cold cream is an emulsion of water and certain fats, usually including beeswax and various scent agents, designed to smooth skin and remove makeup. Cold cream is an emulsion of water in a larger amount of oil, unlike the oil in water emulsion of vanishing cream, so-called because it seems to disappear when applied on skin. The name "cold cream" derives from the cooling feeling that the cream leaves on the skin. Variations of the product have been used for nearly 2000 years." - Per Wikipedia

It is basically grease emulsified in water- so would have effect like the other "grease" products mentioned.

I do not think the brand is important, though the source/type of grease will vary brand to brand - so there may be slight differences.

Try olive oil- you probably have it at home.

11-04-2021, 05:48 AM   #8
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Thank you for your input guys. Here's another one. Taken with a Volna-9 and a ~40mm extension tube. It's really hard to align the lens and the light so the "dust" is visible at these distances The aperture of my Tessar is broken unfortunately so I can't take any sharper images ATM.

edit: BTW, I'm having a hard time giving likes to posts that tell me my lens is broken
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Last edited by trilean; 11-04-2021 at 05:54 AM.
11-04-2021, 08:49 AM - 1 Like   #9
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Any residue on the lens could produce this. To be frank, the process you used may have done more harm than good, leaving soap residue on the lens. Only detergent should be used and very sparingly.

At this point, I would try a good quality lens cleaning solution to see if it will move the defects you're seeing. You might try soaking the lens in pure distilled water before cleaning (with lens tissue or a clean microfiber cloth) to help soften the debris (always used distilled water!). If the lens cleaning solution isn't working, you might add a small amount of pure ethanol to it (Everclear is a high purity ethanol), and try again. Short of this (if this doesn't seem to help), there probably isn't much you can do.

The use of any oily product (face cream or olive oil) is definitely NOT the way to go. You should never apply any oily product to a lens as it can destroy the coating and will leave residue that is extremely hard to remove (soap has a lot of animal fat in it, and that plus other soap ingredients stick to a lens pretty well and tend not to wash off with water - i.e. "soap scum") .

Good luck with your lens.

Last edited by Bob 256; 11-04-2021 at 11:45 AM.
11-04-2021, 12:09 PM - 1 Like   #10
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Household hydrogen peroxide is usually 3%. It should be a problem if you dilute it anywhere from 4 to 1 through 2 to 1 (water to H202). Probably less harmful to coatings than alcohol in my experience.

If the fungus has etched the coating or even the glass you're going to see that even if the fungus has been removed. Cold cream will probably just partially fill in the etching with grease/wax making it less noticeable until a good cleaning removes the residue.

Sort of the idea behind Edwal scratch remover for film and negatives.
11-04-2021, 01:47 PM - 1 Like   #11
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Get some proprietry lens cleaning tissues, the ones in sachets for glasses etc. I use supermarket ones, check that they are solvent based, not water based.
it's actually next to impossible to get a perfectly clean surface outside of a clean room, and invariably once the element is replaced you wil see slight smears or dust that were not visible holding the element alone against a light. These cheap tissues do leave lint flecks so use a blower. I find that letting them dry out a bit first so that they are only damp not wet works best. I also use dried out ones dipped in acetone (or ether if you have it). Wear plastic gloves so you don't get finger grease on anything. Use a circular motion finishing with a firm movement off one edge.
If solvent + tissue doesn't clean it off then there is indeed some damage to something.
11-07-2021, 08:59 AM - 1 Like   #12
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Thanks for all your feedback! I managed to get the lens pretty clean.

Some notes:
  • My optician told me not to use Acetone as it will destroy the coating. Ethanol is fine though and what they use professionally. His experience is based on Zeiss glass for glasses (as in, those you wear on your nose). I suspect that those coatings may be of lesser quality as glasses are not designed to last as long. Anyhow, Ethanol is ok to use.
  • The two chemists I asked about using hydrogen peroxide said they don't see how H2O2 could react with CaF2 or MgF2 (which is what standard anti-reflexion coating is made of). I can't be sure that applies to Pentax' S-M-C coating but it was certainly reassuring to hear.
  • Olive oil didn't do much of anything. The lenses might have been a little cleaner, but not by much. Also, it's annoying to clean off.
  • Microfiber cloth + Ethanol is fine to remove 95% of the crud. But to remove the last 5% use some proper lens cleaning tissue. I used the one from Zeiss.
My process:
  • Get the lens elements fairly clean with microfiber cloth and ethanol.
  • Put them in a 3% hydrogen peroxide solution for 5min
  • Take them out of the H2O2 and wash in a dish with distilled water.
  • Dry it using microfiber cloth and then use a hairdryer. Yes that will add back a bit of dust, but there are two more cleaning steps coming up. Alternatively I could have put the lenses in the oven at around 50°C.
  • Clean again using microfiber cloth and ethanol.
  • Clean the last bits using lens cleaning tissue.
  • Between mounting the individual lens elements I used a blower to remove dust that just settled on the already mounted elements.
I'm really happy with the result. It's cleaner than I'd expect from a ~10y old lens, certainly much cleaner than its 40+y age suggests
12-01-2021, 01:42 PM   #13
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i got ponds from amazon, you re not going to find US cleaning products in germany as it is difficult for them to comply with the german poisons register , in addition to all the EU requirements. went on same journey 4 years ago.

id avoid the hairdryer.


watch this

Last edited by Sandy Hancock; 12-01-2021 at 01:57 PM. Reason: Coarse language
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