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08-10-2013, 07:25 PM   #1
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Lens separation or fungus?

I just took a chance on an "UGLY" condition Pentax A 20mmƒ/2.8 from KEH for a pretty good price, and I'm on the whole pleased with the condition of the lens. The outside is a little beaten up (a little more than a BGN), but the glass is decent except for some junk on the rear element. Honestly, it looks pretty clear when I put it on a lens and look through the viewfinder, and I don't think it'll change the contrast at all. I'm gonna take it to get some professional help when the repair shop opens on Tuesday. If it doesn't work out, I'll send it back.

For my own curiousity's sake, I'd like to try to figure out what it is. Do I have a fungusy lens, or is it gunk? Should I return it?

(I know I have a thread dedicated to the lens and it's value in the same forum, but this is about fungus…not the lens itself.)

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08-10-2013, 08:52 PM   #2
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Both the A20/2.8 and FA20/2.8 (same optical formula) suffers from the same common problem of lens separation of the third group from the rear.

It's hard to determine from your photo whether the problem is lens separation or fungus. However, if you purchased the lens from KEH, I'd imagine they would have been able to clean the fungus, so it's more likely that it's lens separation.

Lens separation can be fixed, but it requires special skill. Most lens repairers are unwilling or unable to perform this operation.
08-10-2013, 11:24 PM   #3
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yep, that is clearly element separation

QuoteOriginally posted by tom1803 Quote
...it requires special skill. Most lens repairers are unwilling or unable to perform this operation.
That is because most repairers these days find it easier to simply replace a lens than take the time an effort to repair it - I know how to rebuild lenses from scratch - but it does require some skill and some specialized tools.
08-11-2013, 02:14 AM   #4
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QuoteOriginally posted by Digitalis Quote
yep, that is clearly element separation
That is because most repairers these days find it easier to simply replace a lens than take the time an effort to repair it - I know how to rebuild lenses from scratch - but it does require some skill and some specialized tools.
Alright! Clearly element separation, eh? I'm glad I asked—it didn't look like a bacteria culture to me. Thanks.

So with that in mind, here are a few questions:

Can I shoot with it without problems?

If so, would it be worth it to fix it? Could Eric Hendrickson do the job?

08-11-2013, 03:08 AM   #5
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QuoteOriginally posted by keyofnight Quote
Can I shoot with it without problems?
Technically yes you can, but be prepared to some pretty horrendous lens flare if a bright light source is anywhere withing the frame. I had a similar lens separation problem with a K55mm f/1.8 that was given to me - I restored it to new condition one weekend, and it has performed superbly since then.


QuoteOriginally posted by keyofnight Quote
Could Eric Hendrickson do the job?
in all probability yes - re-cementing lens elements is pretty easy (well at least for me)
08-11-2013, 05:57 AM   #6
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I do not know if Eric would be able to do it - however, I would email him and certainly ask. Only if Eric is unable, I do know of a service over in California that does this for old Zeiss lenses (since even Zeiss will not touch their older lenses). In reading their website, they appear to only do it one way, dissemble the entire lens and un-glue all the elements, clean and then re-construct and align the lens from scratch. I don't know if they would touch a Pentax lens, however for an A 20/2.8, I would certainly try.

08-11-2013, 01:15 PM   #7
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I also purchased that lens and the resolution is terrible. Likely separation. Great price--you get lucky sometimes--but if the lens was repairable I wonder if KEH wouldn't have done so?
08-12-2013, 01:16 AM   #8
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So…I asked Eric by e-mail, and he said this: "It does look like separation but I could look at it and see. I have corrected the defect on the 100mm macro's." That's all he said. lol.

I'm gonna shop around tomorrow and the next day to see if the local camera repair shops can do it. (CameraTechs and the Camera Clinic here in Seattle, WA…) If they can't do it, I'll send it to Eric.

QuoteOriginally posted by dms Quote
I also purchased that lens and the resolution is terrible. Likely separation. Great price--you get lucky sometimes--but if the lens was repairable I wonder if KEH wouldn't have done so?
You bought the same exact lens from KEH? Or did you buy the same kind of lens elsewhere with the same problem?

I haven't gotten the impression that KEH repairs everything that comes into their shop—even though that's what they'll say on their website and on the phone. I got the impression that they'll only do so much to repair anything they sell. This is the third thing I've bought from KEH, so my experience is limited.

QuoteOriginally posted by interested_observer Quote
In reading their website, they appear to only do it one way, dissemble the entire lens and un-glue all the elements, clean and then re-construct and align the lens from scratch.
Oof…that sounds expensive. lmao. I'll see what they say. (:

08-12-2013, 07:20 PM   #9
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Yes I purchased the exact same lens and after trying it (the pictures were very soft) I returned it. It was shortly before it was purchased by you. (I forget if there appeared to be another purchase between mine and yours.)
08-12-2013, 07:30 PM   #10
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BTW I have purchased a number of lenses, hoods, and a camera from them. And they seem to be very conservative in their ratings. And if I ask (and I do) to refund all postage when they make a mistake--they do so w/o any difficulty/discussion. I likely purchased 6 or more pentax lenses and 4 tamron adaptall lenses, and extension tubes, Nikonos III camera, etc. They can be a bit careless--the extension tubes were said to be auto--and I ended up buying the same set twice. But they actually seldom make mistakes and have what I believe are the best prices--given that you can always return stuff. I rate them as the best, and B&H second--but as I live in NYC B&H is not mail order for me--so I really cannot make a fair comparison.
08-13-2013, 02:50 AM   #11
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QuoteOriginally posted by dms Quote
Yes I purchased the exact same lens and after trying it (the pictures were very soft) I returned it. It was shortly before it was purchased by you. (I forget if there appeared to be another purchase between mine and yours.)
I'm gonna send it back myself, in that case. Things are getting pretty risky. If Eric can't fix it, then I'm stuck with it. I know he does great work, but I just don't want to end up stuck with it.
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