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10-23-2008, 10:02 AM   #1
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Constant Blur on the right side

I just realized (dont ask how it took me months to realize this) that all of my pictures are blurry on one side (right side). I removed any doubt regarding aperture and focal length by taking a picture (directly above) of words on a sheet of paper. Its distinctively blurry on the right side of the frame. I have a K20D with a Sigma 17-70mm f/2.8-4.5 DC Macro Lens.

The lens is clean, what else could be causing this?

10-23-2008, 10:08 AM   #2
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Centering defect? Junk on lens (front or back element)? Junk IN lens (fungus)?

Steve
10-23-2008, 10:18 AM   #3
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QuoteOriginally posted by JohnnyDop Quote
with a Sigma 17-70mm f/2.8-4.5 DC Macro Lens
Try a different lens.
I had to return two for decentering defects (fuzziness on one side at certain focal lengths/distances). The first was horrible at multiple focal lengths. The 2nd was good except for a smaller area at 19mm. I haven't tested the 3rd enough yet...usually needs a vacation w/ a variety of pictures for me to see it...
10-23-2008, 12:51 PM   #4
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What is a Centering Defect?

QuoteOriginally posted by stevebrot Quote
Centering defect? Junk on lens (front or back element)? Junk IN lens (fungus)?

Steve


10-23-2008, 01:03 PM   #5
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QuoteOriginally posted by JohnnyDop Quote
What is a Centering Defect?

An optical lens defect that results in one side of the image being out of focus relative to the rest of the field of view. The DA* 16-50's are "famous" for this. I had 3 of them with this type of defect. I personally have never owned a different lens that had this problem. I agree with kenyee: try another of your lenses to see if it is still there. If it is gone, then you have confirmed it is the lens. You will have to send it back for repair or exchange.
10-23-2008, 01:33 PM   #6
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The physical reason for the centering defect is an internal lens was not manufactured perfectly concave or it wasn't installed perfectly centered, etc. If you look at an internal diagram of a lens, these internal parts move around as you focus. That's why it only appears at certain focal lengths/distances.
Sounds like you have a particularly bad copy with either the front or rear (the non-moving pieces) being asymetric. That's why you see yours at all focal lengths.

Try a different lens. If it works fine, it's the 17-70. If it doesn't, your camera body is messed up...
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