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10-25-2013, 05:59 PM   #1
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Well crap, looks like a bad lens

Really odd one for me: lens looks fine, nice and clean, focuses smoothly, aperture blades are great. When it works, I get great pictures.

However, tilting the camera up then down (or down then up, or side to side) can result in the lens suddenly losing infinity focus. The exact degree is variable: sometimes it will focus on something no more than 10 metres away, sometimes no more than 5, sometimes as low as no more than 1.5-2 metres. And when it does that the distortion it shows is bad. A pair of sample photos, straight OOC, where both are as focused as possible show what I mean.

(The bike is probably 3 metres away. The wall is 1.5 to 2 metres, at most, possibly even closer.)

Anyone ever seen anything like this before and have any idea what it might be? (I've already contacted the person I bought it from to see if I can return it, but no word yet.)

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Last edited by g026r; 10-25-2013 at 06:27 PM.
10-25-2013, 06:07 PM   #2
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I'll wildly guess massive decentering of an element within the lens
10-25-2013, 06:10 PM   #3
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Agree, and since it seems variable it's possible something, one of the lens elements maybe, is loose inside. It's possible someone took it apart to clean and never got it back together correctly.
10-25-2013, 06:28 PM   #4
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QuoteOriginally posted by jatrax Quote
Agree, and since it seems variable it's possible something, one of the lens elements maybe, is loose inside. It's possible someone took it apart to clean and never got it back together correctly.
When I noticed it was variable I started wondering about the elements being loose. Fingers crossed that I can get a return.

Otherwise I guess I've got an "art" lens unless I can manage to fix it myself.

10-25-2013, 06:57 PM   #5
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QuoteOriginally posted by g026r Quote
When I noticed it was variable I started wondering about the elements being loose. Fingers crossed that I can get a return.

Otherwise I guess I've got an "art" lens unless I can manage to fix it myself.
If you purchased the lens new, you have a one year warranty. It might be easier to have Pentax repair it under warranty. All you need is a copy of your dated receipt. CRIS handles Pentax warranty issues.
10-25-2013, 07:05 PM   #6
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It's a Carl Zeiss Jena 50mm, so I doubt it's under Pentax warranty (check the EXIF). Some might say its a variation to delight in, but I'd guess an element has come adrift, too.
10-25-2013, 07:29 PM   #7
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QuoteOriginally posted by RobA_Oz Quote
It's a Carl Zeiss Jena 50mm, so I doubt it's under Pentax warranty (check the EXIF). Some might say its a variation to delight in, but I'd guess an element has come adrift, too.
Ha. I forgot I had added the lens as a keyword when I imported the files off the camera.
10-25-2013, 11:39 PM   #8
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That lens will be an automatic instagram (-or-whatever-you-call-it) wonder!

It doesn't have the correct focus, blurry, all-over... I say instagram-perfect!

10-26-2013, 12:44 AM   #9
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1. Put on Ebay
2. Label as 'Zeiss Holga'
3. ????
4. Profit from hipsters
10-26-2013, 01:17 AM   #10
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Jeez someone forgot to install one of the glass elements or even reversed one! Horrid!
10-26-2013, 05:37 AM   #11
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"Sharp in the center, with a dream-like quality near the edges!"

Sounds like the description of a Lensbaby or many old "eastern-bloc" lenses (like a CZJ 50!)...
But, yeah, there is totally a loose/ misaligned element in there somewhere!
10-26-2013, 09:42 AM   #12
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Heard back from the seller. They're willing to either refund or repair.

With the lens detached from the camera, I gave it a little turn close to my ear. There's a very faint "clink" noise when I do that, like two pieces of glass touching. All who called loose element are right from the sounds of it.
10-26-2013, 10:56 AM   #13
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If the lens requires an adapter, it could also be loose adapter, possible with light leaks. But decentering is also a good diagnosis.
10-26-2013, 11:10 AM   #14
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QuoteOriginally posted by drypenn Quote
That lens will be an automatic instagram (-or-whatever-you-call-it) wonder!

It doesn't have the correct focus, blurry, all-over... I say instagram-perfect!
Yes, as long as he remembers to compose the shot as poorly as possible as well.
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