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06-11-2012, 08:10 PM   #1
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Normal behavior for DA 21mm lens?

I received the DA 21mm lens as a gift a few years back, but never really examined to see if there were any problems because I wasn't aware of any Q/C issues at the time and trusted it to be fine straight from the factory. I also didn't use it very much, since at the time i was using my 18-250mm zoom lens more. When I did use my 21mm lens, I typically wasn't using it for landscape, but instead for portraiture or other uses where I tried to blur out the background.

Now however, I have been using my prime more and more often. I examined a picture I took earlier and noticed that while the center was pretty sharp, the right side of the lens was pretty darn blurry and the left side wasn't too bad at all. When I look at the photo I would say the blurriness affects probably ~ 1/4 of the right hand side of the photo. The right side is definitely blurrier than the left side. How normal is this sort of behavior for this type of lens? Is there anything I can do about it? Can someone show me a picture of the corner performance with their 21mm? Thanks!

The pictures I included are all crops; the first is the center, the second is the left hand side and the third photo is the right hand side.
K-5, DA 21mm, 1/640s, 5.6, ISO 80. Image processed with DxO.

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06-11-2012, 08:26 PM   #2
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Decentering is a common problem, not with the DA21 in particular, but with many lenses. If it's under warranty I'd get it looked at.
06-12-2012, 11:47 AM   #3
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I see. Thanks. It's probably out of warranty, but I'll see if they will do anything about it anyways.
06-14-2012, 03:42 PM   #4
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I contacted customer service and they were unable to get an estimate for me. Does anybody have any past experience on how much it costs to fix a decentered lens?

06-15-2012, 02:01 PM   #5
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I've asked the same questions, and nobody has replied. I read a pretty extensive article written by a lens rental company that has taken lenses apart to try and fix decentering, and they said it's very complicated and time consuming. Interestingly I've heard lots of people talk about why it exists but precious little about fixing it.
06-15-2012, 07:58 PM   #6
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It would be interesting to know how/if decentering is ever actually repaired, particularly in modern lenses. There have been many reports on the forum of decentering, and some reports of lenses being replaced under warranty for it, but I don't recall any instances of lenses being repaired.

Paul
06-16-2012, 02:49 AM   #7
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I suggest emailing Eric
06-18-2012, 04:57 AM   #8
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QuoteOriginally posted by twitch Quote
I suggest emailing Eric
+1 if you're in the US. Otherwise, there are several repair shops in most urban areas that could look at it for you. But from your crops it's hard to tell if the problem is decentering or DOF limits. Try to shoot an even scene, like a large brick wall, to confirm the problem. Shoot it at different apertures. You'll be able to confirm that the problem is with the lens and not the shooting parameters.

06-18-2012, 12:28 PM   #9
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Yeah, I'm going to go ahead and send the lens to Eric to evaluate. Once I noticed the issue I can see it in every photo taken at a distance -- right side always blurrier than the left.

I found some postings of people describing (a little bit) how they fixed a decentered lens, but I've forgotten the keywords I used to find the link otherwise I would've posted it. At least it means that it can probably be fixed.
06-18-2012, 10:23 PM   #10
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QuoteOriginally posted by tibbitts Quote
It would be interesting to know how/if decentering is ever actually repaired, particularly in modern lenses. There have been many reports on the forum of decentering, and some reports of lenses being replaced under warranty for it, but I don't recall any instances of lenses being repaired.

Paul
Get a new lens. In case that compounds don't fit there is no little screw to adjust for decentering. Under warranty you do not need to pay otherwise decentering may not be fixable or you don't want to pay the bill.
07-08-2012, 09:24 PM   #11
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QuoteOriginally posted by zapp Quote
Get a new lens. In case that compounds don't fit there is no little screw to adjust for decentering. Under warranty you do not need to pay otherwise decentering may not be fixable or you don't want to pay the bill.
Well, got it back from Eric and this is what he said:

"Actually another one just like yours with the exact same problem came in the same day. I tried to help him and find out why the alignment isn't right. Or try to correct the focus problem. The is nothing I can really do to fix the problem. All I can do is rotate the internal optic and hope this fixes the problem. I also feel that the front focusing optic is trying to do it's best to capture the image on the edges and keeping them in focus"

Unfortunately, lens is not under warranty.
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