# De-centered 17-40L - worth repairing?



## wsheldon (Sep 3, 2013)

My 7 year old 17-40L appears to have developed a moderate amount of de-centering, with the left side softer than the right from 17-24mm. I confirmed it isn't a focus issue by inverting the camera are re-shooting without refocusing. It's apparent at 100% and somewhat at 50% (when looking for it), but not really at web sizes. It's actually more obvious on the 50D APS-C than 6D FF, probably due to the finer pixel pitch pressing the resolution limits.

I realize this is a pretty common problem with this lens, and the borders and corners typically aren't stellar anyway, but it's bugging me and I'm considering having it repaired. Any experiences (good or bad) having this kind of optical alignment work done on UWA zooms? Given the relatively low price of this lens new, I'm tempted to sell it off (with disclosure) and trying a new one under warranty.

Advise appreciated.


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## bvukich (Sep 3, 2013)

Are you a CPS member? It may not be that expensive to fix.


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## wsheldon (Sep 3, 2013)

bvukich said:


> Are you a CPS member? It may not be that expensive to fix.



Not currently, but I have the gear points to join at the Gold level so that's an option. The discount might pay for the membership at least.


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## clifton425 (Sep 3, 2013)

My 17-40 also had a de-centering problem that became objectionable when I went from a 5D to the 5D2. Sent it to Canon with a poorly worded repair request and it came back different, but no better. Sent to Canon again with a carefully worded repair request and it came back with all corners exactly the same. Cost was reasonable and the lesson is to be careful what you ask for.

This lens finds less use in recent years as the new 24-70 f/2.8 II is much sharper at every focal length and it is so easy to do multi-shot panorama.


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## wsheldon (Sep 3, 2013)

clifton425 said:


> My 17-40 also had a de-centering problem that became objectionable when I went from a 5D to the 5D2. Sent it to Canon with a poorly worded repair request and it came back different, but no better. Sent to Canon again with a carefully worded repair request and it came back with all corners exactly the same. Cost was reasonable and the lesson is to be careful what you ask for.
> 
> This lens finds less use in recent years as the new 24-70 f/2.8 II is much sharper at every focal length and it is so easy to do multi-shot panorama.



Interesting - what did the "magic word" turn out to be that got you the better results?

Thanks.


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## Mt Spokane Photography (Sep 3, 2013)

http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover

Its certainly worth repairing, unless there is more to the problem than simple decentering. For some lenses, its just a 5 minute adjustment of the front element.


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## wsheldon (Sep 3, 2013)

Mt Spokane Photography said:


> Its certainly worth repairing, unless there is more to the problem than simple decentering. For some lenses, its just a 5 minute adjustment of the front element.



Ok, I guess I'll try registering for CPS Gold and give it a shot. That's one of my older lenses and it's seen a lot of road time, so a good cleaning wouldn't hurt either.

Thanks for the replies.


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## Invertalon (Sep 4, 2013)

If it is real bad I am sure they can correct it.

I had a 17-40 I got refurbished that was decentered on the right side... Sent to them twice and they could not correct it, even when I send with examples and all that. It was fine at 17mm, bad at 40mm.

Returned it and got a brand new one that was perfect on both sides. So I am happy now.


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## wsheldon (Sep 8, 2013)

wsheldon said:


> My 7 year old 17-40L appears to have developed a moderate amount of de-centering, with the left side softer than the right from 17-24mm. I confirmed it isn't a focus issue by inverting the camera are re-shooting without refocusing. It's apparent at 100% and somewhat at 50% (when looking for it), but not really at web sizes. It's actually more obvious on the 50D APS-C than 6D FF, probably due to the finer pixel pitch pressing the resolution limits.



To update my original post - I spent some more time with the 17-40L on my 6D at a local botanical garden, and I've decided it's really not that bad at my usual landscape apertures (8-13). One potentially important difference is that I took off the B+W UV filter I customarily use (to complete the weather sealing), and I also mounted the hood carefully since learning that partial vignetting from a crooked hood can cause edge sharpness issues with UWA lenses. I was pleasantly surprised compared to my experience with this lens on my 50D, and only at 17mm was I somewhat disappointed in the corners after basic PP in Lightroom.

Here are some examples:

23mm f8: http://sheldon-photo.smugmug.com/Personal/Zoos-Gardens/Botanical-Garden/i-9ShBpdM/A

22mm f13: http://sheldon-photo.smugmug.com/Personal/Zoos-Gardens/Botanical-Garden/i-287ZnF6/A

20mm f13: http://sheldon-photo.smugmug.com/Personal/Zoos-Gardens/Botanical-Garden/i-mLXsGjk/A

17mm f13: http://sheldon-photo.smugmug.com/Personal/Zoos-Gardens/Botanical-Garden/i-MnN42bX/A

(on the 17mm shot, there's "smearing" in the upper-left corner in the tree branches and corners on the foreground aren't great on either side, but this is WAY less obvious than on the 50D)

Of course it's not up to the level of the new Sigma 35 1.4 DG, but I can certainly work with it considering the flexibility.
http://sheldon-photo.smugmug.com/Personal/Zoos-Gardens/Botanical-Garden/i-khsnRHN/A

Thanks for all the input, but I guess I'll just keep shooting and not rush it off to Canon (yet).


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## Mt Spokane Photography (Sep 9, 2013)

wsheldon said:


> wsheldon said:
> 
> 
> > My 7 year old 17-40L appears to have developed a moderate amount of de-centering, with the left side softer than the right from 17-24mm. I confirmed it isn't a focus issue by inverting the camera are re-shooting without refocusing. It's apparent at 100% and somewhat at 50% (when looking for it), but not really at web sizes. It's actually more obvious on the 50D APS-C than 6D FF, probably due to the finer pixel pitch pressing the resolution limits.
> ...


 
At small apertures, you should not put up with issues, get it fixed.


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## Jim O (Sep 9, 2013)

Mt Spokane Photography said:


> At small apertures, you should not put up with issues, get it fixed.



+1


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## ejenner (Sep 14, 2013)

I had a similar issue that I only noticed on FF. It cost me ~$200 (and 2 trips) to the service center to get it close to 'perfect' (it's still not spot on at 17mm, but OK - I just need to check the focus on the left side).

Just FYI in case you decide you can't live with it.


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