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02-12-2010, 05:17 AM   #1
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Question about an old lens , fungus?

Ok, so I finally got my K50 f1.2 lens bought from ebay.
Fast delivery, paid roughly 384$ including S&H so price was ok for the description (IMO).

"Lens in very good condition. No scratches, dust or fungus on elements. Though if you look through the lens in bright light, you will see a very minor imperfection to the inner elements which I believe is imperfection to the gluing of the elements. It is almost invisible and very faint. This is very minor and very difficult to notice unless you are looking for it. It does not affect picture quality. The lens has been cleaned and as you will notice in the pictures that there is evidence of this on the front name ring. There is a slight play in the focusing ring but again only minor and does not affect function. The body is very good with only minor marks and no noticeable scuffs or dents. I have described the condition of this lens as best as I can so there will be no surprises. "

Although when I look at the lens one of the elements seem to have some weird shapes or the "gluing" issue that he mentions in the sales description. Could this infact be fungus? (Photos includes as attachment)

The shapes are only visible in one of the edges of the lens and maybe 45degrees of the full radius. Back and front glass are clean and scratchfree.

I've checked out the lens in general and it has normal wear and tear on the metal casing and one dent in the "A" letter on the front Asahi text. Otherwise the lens seems to be in good shape, I just cant figure out the weird shapes on the outer rim of one of the inner elements.

Can I verify for sure if my finding has any negative impact on the optical quality of this lens?Should I worry about these shapes, send it for cleaning maybe? Or ask for full or partial refund?

The description did say fungus free..
Apart from the weird shapes there seems to be some slight play in focus ring if moved quickly (this was in description of the sale so Im aware of it already), could this be some loose screw or grease that has dried up?

Attached Images
     
02-12-2010, 05:26 AM   #2
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Forgot to mention that I've taken some quick shots with this lens and I dont see any issues when pixelpeeping.
F1.2 through F5.6 .

Bokeh looks lovely (imo) as always with f1.2 lenses.
02-12-2010, 09:10 AM   #3
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Investigated this a bit more.
Looks like very mild case of lens separation.

Afaik this lowers resell value. Any idea how much it would lower the price of a normal $400 going rate for these lenses in mint condition? *is going to ask for partial refund*
02-12-2010, 11:23 AM   #4
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That sounds like an accurate description to me. Let's say you are the seller. Above are the best photos you can manage of the flaw. You don't know what it is either. You put the lens up for auction, disclose the condition, and someone else wins it. If they ask for a partial refund based on the conditions you spelled out in the listing, would you be willing to pay it? I think the seller has an argument that the condition didn't hurt resale value when you bought it.

02-12-2010, 12:08 PM   #5
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Ok, so I can consider the value I bought the lens to be pretty fair, so I should be good to go and use these lens without affecting photo quality ?

The pictures above are taken by me. No photos of the actual internals were on the ebay auction.
02-12-2010, 12:37 PM   #6
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Was this lens on Ebay UK? I think I remember it, considered buying it but didn't have the money.
Minor lens separation is annoying but shouldn't have much effect on image quialty. If it is sever then it will reduce contrast but as it stands in your lens the effect should not be detectable. I have a Zeiss Planar macro with much more separation but doesn't appear to have athat much effect. It looks worse than it is in the photo bellow due to the lighting and viewing angle.

02-12-2010, 12:41 PM   #7
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I think of element separation as a big unknown. (Or it may indeed be a manufacturing defect.) It's hard to tell exactly what it it without trying to clean it. It often just looks "different". It's not a simple repair, and if it's small it's not worth the effort. I have two lenses with it, and they haven't gotten worse over a couple of years. I don't know about the longer term. I also don't see a dramatic impact on images. I would just try to ignore it.
02-12-2010, 11:28 PM   #8
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Thanks all I think Ill just learn to love this lens even with minor defects.
The defect is very small, and there's not even any rainbow coloration when viewing from any angle. Light from above, below. Fully open aparture or closed.

Could only detect it if I view it from one angle and when "looking" for it. The seller told me it had been this way for a long time and it hadnt progressed.

I'm willing to believe him since he was open and did list this defect in description. It's just the first time I see this in one of my own lenses. Apparture is clean, no fungus. Just this tiny little glueing defect.

Taking the lens for a spin today, the softness of background when its apparture is real wide is very nice. So hopefully going to get some nice shots showing beautiful bokeh aswell.

02-12-2010, 11:33 PM   #9
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QuoteOriginally posted by MattGunn Quote
Was this lens on Ebay UK? I think I remember it, considered buying it but didn't have the money.
Minor lens separation is annoying but shouldn't have much effect on image quialty. If it is sever then it will reduce contrast but as it stands in your lens the effect should not be detectable. I have a Zeiss Planar macro with much more separation but doesn't appear to have athat much effect. It looks worse than it is in the photo bellow due to the lighting and viewing angle.

It was. Photos turn out great and the seller was very accurate with the description so I have decided to keep this gem.
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