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11-01-2009, 07:23 AM   #1
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fungus in SMC 50/1.2

I would like to get some advice on lens fungus from more experienced users.

I was offered an SMC 50/1.2 lens (not the A version) for a good price (~320 USD) by a fellow pentaxian. He let me try the lens before I buy it.

The lens is in perfect condition mechanically, the glass is clean, without any scratches, and optically the lens seems far better than my copy of FA 50/1.4. It has more contrast and resolution at f/2 and at f/8 too (!). Some small dust particles can be seen through the glass, but I do not consider it an issue.

However, today I discovered that if you look through the lens toward light and intentionally focus your eye somewhere between the front and the rear glass of the lens some tiny, fractal-like pattern can be seen at the edge of a glass element inside the lens. It's not easy to see, and so far I have not discovered its effect on the photos. I have succesfully made a picture of it with a macro lens.

Is it, in your opinion, fungus?

If it is, has anybody experience in cleaning of this particular type of lens? I mean, is it possible to dismantle an SMC 50/1.2 and clean the optical elements at all? As far as I know, some lenses are not easy to disassemble. What would be the reasonable cost of such cleaning process?



11-01-2009, 07:41 AM   #2
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I don't think that is fungus. To me, it looks more like the separation of 2 elements. I have seen it before with other lenses (like an M40/2.8), and it looks pretty much exactly like that. More regular pattern than fungus and almost always starts at the edge. These problems really can't be fixed economically, because the elements in question would need to be separated and reglued which is a difficult process. Luckily, that will only affect your photos at the widest aperture, and would most likely only introduce a slight loss of sharpness and contrast at that aperture. You might not even notice. Sucks to see this happen to such nice lenses, because there isn't much you can do about it.
11-01-2009, 07:43 AM   #3
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First of all, $320 for K 50/1.2 isn't such a great price. It's not bad, but not really good either. Second of all, that is totally fungus, which IMHO does make the price expensive.
11-01-2009, 07:44 AM   #4
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Ah lens separatioins sounds more right! :-D Either case, I'd personally pass on the offer. For that price, you can get a 50/1.2 sans problems. If it were the A 50/1.2, though... that would've been another story.

11-01-2009, 08:09 AM   #5
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arpaagent:
Thank you, this seems more of a problem than the fungus would be
I planned to use the lens on my film bodies too, I wonder if this separation inluence the picture quality more on film than on cropped digital.

RawheaD:
Where do you guys buy lenses? I look around on ebay.com, ebay.de, ebay.at, ebay.fr etc. almost everyday for the lenses I am interested in, but I could not find any SMC 50/1.2 under 350-400 USD – not including post charges, but do including the possibility of additional customs and taxes (I live in Europe).
11-01-2009, 09:54 AM   #6
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QuoteOriginally posted by h734790 Quote
arpaagent:
Thank you, this seems more of a problem than the fungus would be
I planned to use the lens on my film bodies too, I wonder if this separation inluence the picture quality more on film than on cropped digital.

RawheaD:
Where do you guys buy lenses? I look around on ebay.com, ebay.de, ebay.at, ebay.fr etc. almost everyday for the lenses I am interested in, but I could not find any SMC 50/1.2 under 350-400 USD not including post charges, but do including the possibility of additional customs and taxes (I live in Europe).
there's also keh.com but ebay and the forum's marketplace are ahrd to beat
11-01-2009, 10:38 AM   #7
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Yeah, that is some sort of separation. If it were in good shape overall, the price may be reasonable but not under the circumstances. These lenses aren't as rare as I once thought either.

As far as cleaning these f1.2 lenses, I would send them to a professional which would run from about $55-75 USD.
11-03-2009, 02:05 AM   #8
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Agree with kristoffon. Stick around here for Pentax gear, especially K-mount. I have had nothing but pleasurable experience dealing with forum members with classifieds. KEH is good for BGN listed items (and if the sample you get is bad, you can always return it for a refund).

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