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EF 24-70 II returned from service - need advice

Started Feb 4, 2019 | Questions thread
WindwardHaole Senior Member • Posts: 1,550
Re: EF 24-70 II returned from service - need advice

The best answers to what you are seeing and why will possibly be found in Lensrentals.com blogs about lens aberrations' causes and maybe corrections. The following blogs are hopefully a good start.

https://www.lensrentals.com/.../testing-for-a-decentered-lens-an-old-technique-gets-a-makeover

I've included two of Roger Cicalas' comments:

"An element can also be tilted to one side or another. Strictly speaking this is not decentering, but it can have similar effects, so people often say a lens is decentered when in fact it’s tilted. In this case one axis may remain sharp, but the other will be out of sorts. If the tilt is side-to-side, the top and bottom of the image might be fine, but both sides soft. If it is corner-to-corner the top right and lower left corners might be fine, while the top left and lower right are soft. High quality lenses usually have one or more elements on which the tilt can be adjusted by two or three elliptical collars.

"Zooms can decenter anywhere throughout the range. We test at both ends and in the middle of the range. BUT most zooms are going to be slightly decentered at some point. It's really quite rare to find one that isn't at all."

Important to remember that "tilt" is a "centering" issue, my guess is that what you are seeing is tilt.

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