If you have perfect/acceptable left AF with D800 and 24-70mm, I need your help

Started Jun 28, 2012 | Discussions thread
mrwilkins Forum Member • Posts: 70
Re: If you have perfect/acceptable left AF with D800 and 24-70mm, I need your help

Since that was a long post with pictures interspersed, I wanted to post a quick summary:

Testing with a 17-35 f/2.8 zoom yielded more blurry images on the left side of the frame than the right, but I suspected a lens issue because the images were more blurred on the horizontal axis than vertical, which suggested astigmatism, a lens property.

I repeated the test with a 35mm f/2 prime and all three images came out looking quite sharp, with the left side focus point being the best by a slight bit.

While the OP's issues are a lot more serious than anything I saw and look like a flat-out calibration error on the camera's part, it's important to keep in mind that most zoom lenses, even expensive, high-quality pro lenses, don't maintain critical sharpness or field flatness across the entire frame when they're used wide-open or at one end or the other of their focal length range. Testing with a prime lens is a very important step, I think, if one wants to rule out lens problems contributing to the issue.

Edit: And, if you want to see ALL the problems your lens exhibits, the D800 will hold them up in front of your nose. The 17-35 f/2.8, which I love using, also exhibits all kinds of chromatic aberration, and at some level my choices are just to accept it and try to clean it up after the fact (which doesn't always work) or use a different lens.

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