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07-18-2015, 10:59 AM   #1
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decentering?

Just curious, could someone post a photo example of decentering?

Thanks

Randy

07-18-2015, 12:22 PM   #2
osv
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https://www.dropbox.com/s/0gxrx5uebxgstlk/DSC03353at2point0.JPG?dl=0

click on the pic, then click on the % number in the center, it'll blow up to 100%, you can scroll around to see which side is decentered.

i also have a bunch of decentering comparisons on my website.

Last edited by osv; 07-21-2015 at 12:32 PM.
07-19-2015, 04:31 PM   #3
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QuoteOriginally posted by osv Quote
https://www.dropbox.com/home?preview=DSC03353at2point0.JPG

click on the pic, then click on the % number in the center, it'll blow up to 100%, you can scroll around to see which side is decentered.

i also have a bunch of decentering comparisons on my website.
Hello and thanks
Unfortunately I don't know much about dropbox... I clicked the link and it asked me to make an account in which I did... went back to your link and I don't see anything just my generic home page

Thanks

Randy
07-19-2015, 05:34 PM   #4
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QuoteOriginally posted by slip Quote
Just curious, could someone post a photo example of decentering?

Thanks

Randy
I don't have an example on-line. Well, maybe I do, actually, here on the forum, but it's been so long I don't remember. But I don't know of other reasons for one edge or corner to have substantially different performance than the others (assuming the body isn't defective, of course.) In my examples, one side or corner of a subject parallel to the sensor is obviously blurry when the other(s) aren't. Are there other reasons for this behavior?

07-20-2015, 03:26 AM   #5
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Hah, yeah, I don't have an example, either. I guess most of us just delete photos that have faults.. and I had my Samyang 14mm exchanged due to decentering.
The way I see it, decentering means that the different sides of the photo are not equal in quality. For example, the right side is blurry, has different CA, and different DoF from the left side. Like, the DoF is not parallel, but diagonal, and the right side has a lot of CA, but the left side has less CA. At least, that is what I found on my copy. When I focused on the stars, for example, half of the frame was sharp, but the other half was OoF.
07-20-2015, 03:45 AM   #6
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A good article with a simple test is LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover
07-21-2015, 12:46 PM   #7
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QuoteOriginally posted by slip Quote
Hello and thanks
Unfortunately I don't know much about dropbox... I clicked the link and it asked me to make an account in which I did... went back to your link and I don't see anything just my generic home page
sorry about that, try this, just hit the escape key when it asks for a login:

https://www.dropbox.com/s/0gxrx5uebxgstlk/DSC03353at2point0.JPG?dl=0

this sigma 24mm lens comparison shows decentered sides vs. good sides pretty well, be sure and view the photo at 100% size:

24mm lens sample variation: Three Sigma 24mm lens and three Canon FDn 24mm lenses compared

view the photo in this link at 100% view size, there are examples of both decentering and a wavy focus area:

35mm lens comparison, second round, Minolta 35/2.8 & Pentax FA35/2, on the Sony a7R.
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