Old glass won't get clean

I've been trying to clean the elements of a 70s vivitar 600 using fibre cloth with hydrogen peroxyd and then wet glass tissues for the finish, but most of whatever was there is still there. It is no fungus or dust or cleaning marks. What is it ? And how can I get rid of it ? I ve been quite forcefull while cleaning, seeing that not much improved... I had the doublet out and tried my best on both elements. Thanks for your opinions. The pics are cellphone but they show enough.

It's best to be very gentle when cleaning coated lenses, and not use any force. Coatings on internal elements are sometimes softer. Tissues/cloths containing silicone (for cleaning eyeglasses) should not be used. I have seen similar spots from coating loss or damage from removed fungus, but you claim that isn't the case. Water damage can also leave spots.

 

If it's a doublet, perhaps it is the start of separation, though that often has an iridescent appearance. I have also seen a similar mottled appearance in some old laminated filters. Whatever the case, it will always look worse with a light, and may not noticeably affect image quality.

Edited May 13, 2020 by m42dave

If it's a cemented pair, as Dave says, sometimes deterioration of some kind happens between the two lenses. I always suspect this if surface cleaning won't shift it. Separation, fungus, or just some kind of chemical reaction in the cement. There's nothing you can do but as suggested, it may not be too bad as to be seen in the image.

If the marks are on the outside surface: forget about them and just live with it if the lens seems to perform well otherwise. I own a number of older Nikkor lenses with that same degree of marks on their front or rear element surface. No idea what they are, but like yours I found them resistant to simple cleaning with peroxide and microfiber cloth. Its some odd type of coating wear/degradation, hazing spots or environmental damage, often on the inside unreachable part of the glass (it looks like its right there on the surface, yet you can't feel any pockmarks or scratches and the coating seems unbroken when examined closely). While it looks terrible and annoys me no end, ironically these lenses are some of the sharpest I own, so the defect may not be optically significant.

 

If the marks are in the center, hovering on a flat plane between the elements, you've got a chemical reaction in the cement as mentioned in previous replies. The seriousness of this flaw hinges on whether it seems to have any impact on your photos, and whether the defect is stable, slowly getting worse, or rapidly getting worse. Usually when it looks like this specific pattern, the decay is stable (about as bad as its ever going to get). As long as you are happy with the performance of the lens, you can keep using it for quite some time. The cement can (usually) be removed and replaced in such a doublet, but DIY methods are tricky and its an expensive repair if done professionally. I would just continue to use the lens, while casually keeping an eye out for a better replacement copy without the problem (if it really bothers you).

Edited May 13, 2020 by orsetto

Looks like fungus damage to me. This is a pretty good write-up: Cleaning Fungus in Camera Lenses

 

The usual mix is 50:50 ammonia and hydrogen peroxide. The article has it diluted quite a bit but most people use it full strength. I'd use caution with their other recommendations.

Fungus may have etched the glass at some point in the lens' life.

Since OP said they already performed a thorough cleaning with peroxide prior to posting this thread, any external fungus should now be sterilized (if indeed it was still active: if these marks are etchings from fungus excretions, they're fairly ancient). If these marks were caused by fungus, and the marks are located in the cement between the elements, there might still be contamination potential if the fungus remains "live". No way to neutralize it for certain unless the doublet is taken apart and the cement replaced. Check the mirror elements very carefully: if fungus has spread to those surfaces it could become very problematic (this type of mirror is not easily cleaned without damage).

 

OTOH, if the marks are strictly on the external surfaces of the doublet (nothing in between, nothing on the mirrors), and they've been scrubbed with peroxide, I wouldn't worry too much. Chances are its leftover etching from long-expired fungus, or a weird manifestation of coating wear/decay unrelated to fungus. If you accumulate enough old lenses, sooner or later you end up with a few that have really odd glass or coating issues that defy easy explanation. Fungus damage comes in a wide variety of appearances, conversely some issues that look like fungus aren't fungus at all (as seen in random examples of silver-nose pre-AI Nikkors and vintage Mamiya).

A fungal infection that has etched into the glass, either as spiderly scratches or pitting, is impossible to remove without virtually machining elements and repolishing.

A lens that old is probably not worth the work in salvaging from such a problem. I would not disassemble the lens for risk of allowing any active fungal spores to spread to other equipment.

Thanks so much everybody. Well I didn't mean doublet as in 2 cemented elements. They are actually 2 distinct elements and I took them out and could clean each easily. The first (front) element is by far the worst. The other one is not really bad. I learned a lot with everyone's input and I'm ready to dismantle the lens again. I couldn't test the lens yet. The rear elements also need attention and I should clean them first. Thanks again everyone. Good shooting !

And it doesn't seem to be coated at all. Can someone confirm ? It's the old multi-branded 600 f8 which comes in 2 pieces which you screw together.

If there is no etching then you could try the following. Mix Ammonia liquid and Peroxide Fifty-fifty and apply immediately to the glass. It will remove all fungus easily. Mix only just before applying. Romney prescribed this in his Book/Manual. Best wishes. SP

Ok. Will try that one, too. Thanks.

Is there white paint or strips of white paper inside the barrel of that lens? What are those huge areas of bright reflection? Those would worry me much more than a few minor smudges on the glass.

 

And how much time is worth spending on a cheap old lens? The colour fringing is going to be horrendous for a start.

When cleaning telescope mirrors, I found ammonia worked when all other cleaners failed.

Hi Rodeo. No. I was shining through with a torch which makes things look much worse.. In fact it's all black inside. Yes it's a cheap lens for most, but this is relative. Depends a lot on your income. We're african country here ! I'm even amazed sometimes at some shipping costs.

Hi John. I could try amonia. Never been shopping for that but I can try. Thank you !

A fungal infection that has etched into the glass, either as spiderly scratches or pitting, is impossible to remove without virtually machining elements and repolishing.

A lens that old is probably not worth the work in salvaging from such a problem. I would not disassemble the lens for risk of allowing any active fungal spores to spread to other equipment.

 

There are active fungal spores everywhere all the time. They only time they are a problem if if the lens is stored at relative humidity above 50% and temps above 30 C degrees, and in the dark. UV kills fungus, and low humidity and/or temps will not allow it to grow. I have over 100 vintage lenses, many with traces of fungus, happily living together in dry containers and I have never had any problems.