fungus does coating damage?

kuuan · Expire: 2014-12-26

there is a lens I wanted to buy, but it has fungus on the rear lens. I have never had this kind of fungus with a redish area and a black point at it's core before. I suppose that it destroyed the coating and therefore cannot simply be cleaned off.

but because I never have had this kind of fault before I came here to ask:
has this fungus destroyed two points of the coating, and therefore it cannot simply be cleaned, and the lens better be avoided?
or do you think it still can be cleaned off, without having to expect deterioration of performance?

please have a look:
original size

somewhat enlarged

thank you for any opinion, cheers, andreas

guardian · Joined: 18 Mar 2009 Posts: 1747

I can only offer you my opinion. It's free and worth every penny! Very Happy

I would not be too put off by that fungus provided:

1. The lens is being sold at a very good price which takes fully into consideration its condition
2. You have capability to disassemble the lens, attack the fungus, and reassemble the lens
3. You are willing to live with a lens which might turn out wholly usable, but not pristine

Even as is that lens likely will take a good picture. Cleaned up it might be slightly better. Depending on price, I certainly think you should give that lens a shot if it's one you want. Minor flaws in the coating will be undetectable in photos.

Pontus · Expire: 2016-08-25

That is a huge rear element!

Langstrum · Joined: 16 Feb 2014 Posts: 351

I'm with guardian, if the price is good, the lens has good reputation, then the fungus is not a real problem, even if they ate some of the coating layer.
I cleaned several fungus lenses and I had one was almost like yours. There wasn't any noticeable effect on the image, except one case I saw a transparent purple dot appeared with HDR shot because the coating at that point was lost on the front glass.
Recently I got a FD 50mm f/1.4 S.S.C for just $15 because the owner sold it "as is". Its glasses were full of fungus, but after cleaning, this lens became really good. So, don't miss your chance.

mo · Expire: 2016-07-30

I am thinking it may be a particle/oil perhaps with fungus growing on it or its "fresh" fungus,Do you have the lens to inspect it more closely?
After buying the primoplan with all its coating damage,if this lens is a good lens and at a great price...it may well be worth the risk. It's a tough call Andreas,but we do know if we pass on one lens, another will come along in better condition and sometimes a better price. Very Happy

kuuan · Expire: 2014-12-26

thank you very much everyone for your kind answers, for sharing your insights!

well, this rear element actually isn't all that big, it is a cheap lens. I had opened and cleaned the same lens before, it is not difficult. I don't have the lens, only downloaded photos.

I agree, from own experience, that fungus usually doesn't effect IQ and also can be easily cleaned. Coating damage on the rear lens however, also from own experience, i am quite wary about. Here it only would be two small spots though and therefore not a big problem.
Still, as mentioned I have never encountered such fungus with real dark black spot in it's core, I wonder if anyone has had experience with this particular kind of fungus and can say more about it.

because it is a cheap lens and because with a bit of patience I may get a clean copy for just 10 usd more I think that it's more clever to give it a pass. On the other hand, just to find out if it can be cleaned or not, I am also still tempted to get it Wink

thank you again,
andreas

mo · Expire: 2016-07-30

For 10usd it could be a valuable learning curve that gives you insight on any future issues with this sort of fungus. I always think trust your gut instinct and let it pass.

kuuan · Expire: 2014-12-26

guardian · Joined: 18 Mar 2009 Posts: 1747

Layer-cake · Joined: 18 Mar 2013 Posts: 560 Location: Cape Town

what type of lens is it if you font mind me asking, might give a clue to what could be expected from the coatings.

kuuan · Expire: 2014-12-26

oh, a humble but fantastic Auto Takumar 2/55. The sale finished, but already I got a different copy copy instead Smile

Layer-cake · Joined: 18 Mar 2013 Posts: 560 Location: Cape Town

Yeah I would probably say thats best considering how cheaply they go for, I would think the coatings would be quite soft on a lens of that era but to be honest I have never seen a scratch on any of the takumars that have come my way!