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Archive 2013 · Dealing with decentering
  
 
DK78
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p.1 #1 · p.1 #1 · Dealing with decentering


Hi,
My first post here though I am a long time reader of this nice forum.

I've purchased a used EF-S 10-22mm lens and quite enjoyed it already - colors are rich, flare resistance is excellent. The annoying thing about my copy is when focusing on far away objects/infinity @10-14mm - the right edge is blurry like hell and only at F/11 the right edge evens with the left. The "upside down" test confirming that this is a decentering issue.

I know that I should send it in for repair but maybe someone knows "home remedy" for that issue?
As far as I know the front element can be adjusted after removing the front ring without further disassembly (IF the front element is the problem). May be someone "tried this at home" and could elaborate?

Thanks!



Jun 12, 2013 at 10:32 AM
RCicala
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p.1 #2 · p.1 #2 · Dealing with decentering


The front element is an adjusting and centering element. With the lens and camera set up on a tripod and opened up so the front element is exposed you can make adjustments and then compare results in live view as you adjust the centering.

There is also a centering set at the rear group, but it requires removal of the PCB and rear barrel to expose. You have to reassemble after each adjustment so that one is not very practical to try at home.



Jun 12, 2013 at 10:41 AM
DK78
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p.1 #3 · p.1 #3 · Dealing with decentering


Thanks! Glad to hear it's doable.
But how can I assure that the decentering caused by the front element? When focusing past infinity - the right edge becomes sharp.
BTW, how many screws are beneath that ring and do I need some kind of thread locker when adjusting is done? (i'm still trying to figure out how to remove that ring without damadging the protruding element).



Jun 12, 2013 at 11:43 AM
RCicala
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p.1 #4 · p.1 #4 · Dealing with decentering


I don't know how to assure it's the front (I suspect that requires Canon targets and software that we will never know about), and truth is it's more likely to be the rear adjustment or something broken within the lens (broken collar on a helicoid, lens mount not flat, bent barrel etc.) but the front is the easiest thing to get to. There are three screws holding the front element on and in most copies there isn't any locktite on them in my experience.




Jun 12, 2013 at 01:08 PM
cineski
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p.1 #5 · p.1 #5 · Dealing with decentering


Whack it with a rubber mallet a few times? ;-). Send it in. It'll come back better than new.


Jun 12, 2013 at 01:35 PM
DK78
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p.1 #6 · p.1 #6 · Dealing with decentering


RCicala wrote:
and truth is it's more likely to be the rear adjustment or something broken within the lens

Oh no, hopefuly it's not
Any tips for removing that sticky ring without scratching the glass?


cineski wrote:
Whack it with a rubber mallet a few times? ;-). Send it in. It'll come back better than new.

The mallet advice is for avoiding the "within specs report"?



Jun 12, 2013 at 02:24 PM
DK78
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p.1 #7 · p.1 #7 · Dealing with decentering


Interesting.
I've searched flickr and at widest settings many of 10-22 images have blurred right edge... also slrgear test of 10-22 showing decentering @ 10mm. May be it's indeed "within specs"?

A few test shots @ 10mm
f3.5
f5.6
f10



Jun 12, 2013 at 07:14 PM
RCicala
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p.1 #8 · p.1 #8 · Dealing with decentering


DK78 wrote:
[Oh no, hopefuly it's not
Any tips for removing that sticky ring without scratching the glass?



If you mean the plastic makeup ring around the front, you can put a very small screwdriver between it's out edge and the filter ring and pop it up. SImpler is to remove the rubber from the zoom ring, remove the single screw under the rubber, and push the entire filter barrel assembly forward taking it and the plastic makeup ring off.

That's simpler to take off, but kind of a pain to line it back up to get it on. It only will go on one way.



Jun 12, 2013 at 08:07 PM
Mike Sowsun
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p.1 #9 · p.1 #9 · Dealing with decentering


I believe the 10-22 front ring is simialr to the 17-40 and you would remove it the same way.

Here is a video that shows you how on the 17-40:

17-40 dissassembly












Jun 12, 2013 at 08:29 PM
Gunzorro
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p.1 #10 · p.1 #10 · Dealing with decentering


DK78 wrote:
Interesting.
I've searched flickr and at widest settings many of 10-22 images have blurred right edge... also slrgear test of 10-22 showing decentering @ 10mm. May be it's indeed "within specs"?

A few test shots @ 10mm
f3.5
f5.6
f10


Looking at your f/3.5 shot, that looks far worse than I remember my copy looking (a few years ago). Even the left side looks poorly.

I'd send it to Canon with a CD of these images, with a full letter of explanation. If the lens is new, they will fix under warranty. If not new, then hopefully you are CPS gold or platinum and will get the discount on repair.



Jun 12, 2013 at 08:31 PM
 

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DK78
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p.1 #11 · p.1 #11 · Dealing with decentering


Thanks all for helping with the ring removal.

2 Gunzorro
Is it really THAT bad?



Jun 12, 2013 at 09:30 PM
Gochugogi
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p.1 #12 · p.1 #12 · Dealing with decentering


The left side looks slightly softer to me. At 10mm, my 10-22 is very sharp in the center and gets progressively softer towards the edges. The softness is more pronounced at infinity than close distance and also at the wider settings. As I zoom the edges get sharper and about 14mm it is amazingly sharp across the frame. Like you, F11 at 10mm sharpens up nicely if you don't mind a wee bit of overall sharpness loss.

Actually your 10-22 looks pretty typical. It would be hard to improve with a home brew fix.



Jun 12, 2013 at 10:11 PM
DK78
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p.1 #13 · p.1 #13 · Dealing with decentering


Gochugogi wrote:
The left side looks softer to me.

Left or right side? The left is soft but just near the border, the blurriness on the right is much more pronounced IMO.
Yes, at close distance my copy is much sharper, even at the edges (at least @ 5.6).

Gochugogi wrote:
Actually your 10-22 looks pretty typical. It would be hard to improve with a home brew fix.

And what are my chances that Canon will come to same conclusion (typical)?




Jun 12, 2013 at 10:30 PM
Pixel Perfect
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p.1 #14 · p.1 #14 · Dealing with decentering


I found decentering to be easily fixed; I walked into my local Canon repair shop and handed my lens over. Cost about $160 to fix on my 24-105L.


Jun 13, 2013 at 02:46 AM
DK78
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p.1 #15 · p.1 #15 · Dealing with decentering


Pixel Perfect wrote:
I found decentering to be easily fixed; I walked into my local Canon repair shop and handed my lens over. Cost about $160 to fix on my 24-105L.


If I were absolutely sure Canon will see my finding as a "problem" - then I would send it in. Gochugogi said the lens look typical and after checking flickr for full-size samples I tend to agree with him... altough IMO the right edge softness is unacceptable for such a praised lens.



Jun 13, 2013 at 11:41 AM
skibum5
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p.1 #16 · p.1 #16 · Dealing with decentering


DK78 wrote:
Interesting.
I've searched flickr and at widest settings many of 10-22 images have blurred right edge... also slrgear test of 10-22 showing decentering @ 10mm. May be it's indeed "within specs"?

A few test shots @ 10mm
f3.5
f5.6
f10


It seems such things are happening with a lot of lenses.

That looks pretty bad on that copy. I don't know something that far off could be in spec.



Jun 13, 2013 at 08:18 PM
RCicala
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p.1 #17 · p.1 #17 · Dealing with decentering


Specs are funny things, but I will say Canon has always been more receptive when I have to send a lens back for an optical issue than other companies. The worst thing I ever hear back is "We readjusted the optics". Often I get "after reevaluation we did find a problem not apparent previously and xxxx was replaced".

With other companies I often just get "we rechecked your lens and it is still within specifications". With Sony I once got "please do not send this lens again, it is clearly within specifications and not further evaluations will be done". And that lens I had sent charts showing a 50% difference in resolution side to side.



Jun 14, 2013 at 12:46 AM
Pixel Perfect
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p.1 #18 · p.1 #18 · Dealing with decentering


DK78 wrote:
If I were absolutely sure Canon will see my finding as a "problem" - then I would send it in. Gochugogi said the lens look typical and after checking flickr for full-size samples I tend to agree with him... altough IMO the right edge softness is unacceptable for such a praised lens.


I showed them pictures where the RHS were soft as mush and the LHS were fine. Lens is good across the frame now.



Jun 14, 2013 at 01:45 AM
Invertalon
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p.1 #19 · p.1 #19 · Dealing with decentering


I have had (2) decentered lenses, one of which was a 24-70 II and the other a 17-40... Sent to Canon and they attempted to fix it, but no help at all. I exchanged the lens for another which was perfect.

Both times thing, both lenses did not get fixed by Canon for whatever reason. I even sent examples and all that. The one improved slightly, but still bad. Exchanged that one too... Learned after that to not even try to get them repaired, just send them back and get another.



Jun 14, 2013 at 02:33 AM
myron lee
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p.1 #20 · p.1 #20 · Dealing with decentering


Invertalon wrote:
I have had (2) decentered lenses, one of which was a 24-70 II and the other a 17-40... Sent to Canon and they attempted to fix it, but no help at all. I exchanged the lens for another which was perfect.

Both times thing, both lenses did not get fixed by Canon for whatever reason. I even sent examples and all that. The one improved slightly, but still bad. Exchanged that one too... Learned after that to not even try to get them repaired, just send them back and get another.



I had two de-centered lens, one was the 50 1.4 and the other 16-35. I sent them both to Irvine, both came back fixed and sharper than ever. In fact, both lens, wide open, are now sharper than most of the internet reviews that post the 100% crops for comparison.



Jun 14, 2013 at 05:01 AM
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