# Check your 11-24L for decentering!



## PhotographyFirst (Mar 4, 2015)

I've been looking at many sample photos from the 11-24 at 11mm. So far I have spotted some copies with poor centering at 11mm. At $3000, you should be demanding perfect performance.

Here is one example. If I am incorrect about my observation, please let me know. Check the lower corners. On a 5Ds, this is going to be way worse. 

https://www.flickr.com/photos/[email protected]/16030615343/sizes/o/

If you need help with checking with centering, I have a 16-35L guide in the education section of my website which shows you how. It applies to all lenses.


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## msatter (Mar 4, 2015)

Thanks for the 16-35L guide and I learned new thing.


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## SPKoko (Mar 4, 2015)

Your 16-35 guide is very nice!

Regarding the centering, I too can see very clearly the difference... Very unfortunately, it is a recurrent problem with many wide-angle lenses: they seem to always have better corners than others. And if you send it to Canon to service it, they return it as you sent it... 

Perhaps that could be acceptable for kit lenses at 18mm or for the 10-18mm, but never for a 3000$ lens!


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## Camerajah (Mar 4, 2015)

I see it,where can I find his 16-35 guide


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## SPKoko (Mar 4, 2015)

Camerajah said:


> I see it,where can I find his 16-35 guide



http://www.johaneickmeyer.com/Educational/Canon1635LIIGuide/35462741_hMfdXc


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## Camerajah (Mar 4, 2015)

thanks


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## Mitch.Conner (Mar 4, 2015)

Is it the lower left corner you guys are looking at?


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## mackguyver (Mar 4, 2015)

I'll test my copy soon, but I saw this on Dpreview yesterday have two notes on this - #1, this photo is from 2/14, so it's likely to be a prototype/pre-production model, and #2, the photo is not of a flat surface and the subject distance in the two lower corners is not the same. I'm not saying it isn't decentered, but this isn't a very good photo to determine whether it is or isn't decentered.

Also, Johan, that's a nice page on your site. I'll have to check it out when I have more time.


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## PhotographyFirst (Mar 4, 2015)

mackguyver said:


> I'll test my copy soon, but I saw this on Dpreview yesterday have two notes on this - #1, this photo is from 2/14, so it's likely to be a prototype/pre-production model, and #2, the photo is not of a flat surface and the subject distance in the two lower corners is not the same. I'm not saying it isn't decentered, but this isn't a very good photo to determine whether it is or isn't decentered.
> 
> Also, Johan, that's a nice page on your site. I'll have to check it out when I have more time.


At 11mm and that distance, I can't imagine it makes a difference.  
Plus the whole left side looks a bit soft on the edge. 

I've seen this in other shots, but maybe they all came from the same lens? Who knows. If true, then did Canon put out a bad lens for testing or did it get bumped and put out of alignment?


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## PhotographyFirst (Mar 4, 2015)

Mitch.Conner said:


> Is it the lower left corner you guys are looking at?


Yes, and the sides. Imagine if this was done on a 5Ds with 50MP. The difference would be pretty huge.


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## PhotographyFirst (Mar 4, 2015)

Also, if you do the centering test like shown on the website, make sure to do it wide open on the 11-24. I did it at f8 on the 16-35L because the corners are so soft wide open on a good copy that it is difficult to do the test for bad copies. 

I really wish Canon comes out with a 16-35L III f2.8 with the f4 IS treatment.


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## Mt Spokane Photography (Mar 4, 2015)

mackguyver said:


> I'll test my copy soon, but I saw this on Dpreview yesterday have two notes on this - #1, this photo is from 2/14, so it's likely to be a prototype/pre-production model, and #2, the photo is not of a flat surface and the subject distance in the two lower corners is not the same. I'm not saying it isn't decentered, but this isn't a very good photo to determine whether it is or isn't decentered.
> 
> Also, Johan, that's a nice page on your site. I'll have to check it out when I have more time.



I also noted that this is not the best photo to test decentering. I'd suggest that anyone checking a lens for decentering to look at Roger Cicala's article.

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


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## dcm (Mar 4, 2015)

You can also use a Zeiss Siemens Star Chart to test for decentering. Roger at Lens Rentals has a nice writeup - http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover

You can purchase one (Amazon, B&H, Adorama, ...) or find a freebie for download (https://www.google.com/search?q=zeiss+siemens+star+chart&tbm=isch)


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## Invertalon (Mar 4, 2015)

Mine is perfect... Checked at all focal length, wide open. Edge to edge, corner to corner... No problems here.


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## PhotographyFirst (Mar 4, 2015)

dcm said:


> You can also use a Zeiss Siemens Star Chart to test for decentering. Roger at Lens Rentals has a nice writeup - http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover
> 
> You can purchase one (Amazon, B&H, Adorama, ...) or find a freebie for download (https://www.google.com/search?q=zeiss+siemens+star+chart&tbm=isch)



That's not a good method on Roger's part, because he assumes people have a test bench where the chart and sensor plane are perfectly parallel. It also seems like you have to test at a close focusing distance only. On an UWA lens, this would require a chart the size of a house to get mid to long field readings. 

The method I describe on my website can be done without a proper testing facility.


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## pierlux (Mar 4, 2015)

Johan, nice website. Some really stunning landscape photos there!

_"... After shooting the first roll of film, I opened up the camera to see how my pictures had turned out by unraveling the canister. To my surprise, I saw nothing and thought my camera was broken! Well, it turned out I needed the minor step of processing the film."_ : LOL!!!


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## privatebydesign (Mar 4, 2015)

PhotographyFirst said:


> Yes, and the sides. Imagine if this was done on a 5Ds with 50MP. The difference would be pretty huge.



No, the difference would be exactly the same at the same output size.


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## PhotographyFirst (Mar 4, 2015)

pierlux said:


> Johan, nice website. Some really stunning landscape photos there!
> 
> _"... After shooting the first roll of film, I opened up the camera to see how my pictures had turned out by unraveling the canister. To my surprise, I saw nothing and thought my camera was broken! Well, it turned out I needed the minor step of processing the film."_ : LOL!!!



Thanks. I still remember that moment like it was yesterday. 
Something kids these days may never experience.


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## geekpower (Mar 5, 2015)

Regarding the section on your guide about infinity focus, isn't the purpose of the "past infinity" part of the focus ring to allow for the effect of different temperatures on the lens?


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## privatebydesign (Mar 5, 2015)

geekpower said:


> Regarding the section on your guide about infinity focus, isn't the purpose of the "past infinity" part of the focus ring to allow for the effect of different temperatures on the lens?



Yes it is. 

And the TS-E lenses focus even further past infinity to give you more control over the plain of focus.


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## PhotographyFirst (Mar 5, 2015)

geekpower said:


> Regarding the section on your guide about infinity focus, isn't the purpose of the "past infinity" part of the focus ring to allow for the effect of different temperatures on the lens?


The 16-35L II isn't parfocal. Thus focus must always change for different focal length settings. Temperature of the lens has little effect on where infinity must be set, in my experience. These lenses are very well designed to withstand thermal expansion. It still plays a roll, but not by any noticeable degree. 

Also, the article is not saying anything about going past true infinity. It is only stating that to achieve infinity, you must not go by the marking and instead there is extra sharpness to be had by going past it a little based on lens variation from copy to copy. The test is to know where you should set infinity focus by knowing the offset for different focal lengths. Setting it to the marking still gives acceptable sharpness for the most part due to the hyperfocal distances. As you can see in the article, the added sharpness is very little but real. 

The lens design also allows for the AF mechanism to hit infinity without hitting the stops when it must rock back and forth. It is important to give a bit of extra room for this to happen. I had a 70-200 lens that was too far out of spec, and at 70mm the infinity setting was too far past the marking, causing the AF mechanism to hit the stops and give up on finding true infinity, even though I could put it manually to true infinity.


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## privatebydesign (Mar 5, 2015)

PhotographyFirst said:


> geekpower said:
> 
> 
> > Regarding the section on your guide about infinity focus, isn't the purpose of the "past infinity" part of the focus ring to allow for the effect of different temperatures on the lens?
> ...



It has nothing to do with zoom parfocal or not, if it did the primes wouldn't go past infinity yet they do.


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## PhotographyFirst (Mar 5, 2015)

privatebydesign said:


> geekpower said:
> 
> 
> > Regarding the section on your guide about infinity focus, isn't the purpose of the "past infinity" part of the focus ring to allow for the effect of different temperatures on the lens?
> ...



That's only true on the TS-E 17. The 24, 45, and 90 do not have that much extra room past the marking. 

It probably has to do with the field curvature of the 17mm when fully shifted.


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