Originally posted by fuent104 Great shot. What is decentering?
Decentering is the result of an individual lens or lens group within a lens unit being out of place. It usually results in photographs with blurring, smearing, and/or doubling along one side. It's more commonly noticed in large-aperture lenses. Stopping down can usually mitigate or correct the problem. To get it fixed, however, the lens will need to be sent to the manufacturer. With my lens (the 28-75), it only affects the leftmost tenth of the image, and it's only noticeable wide open at the wide end of the focal range. Wide open, at 40mm, it's gone, and at 28mm, by f/5, it's much less noticeable.