02-17-2013, 09:47 AM
Did you, or did you not, focus manually with live view, to get the center sharp? That is step one.
If it gets sharper/ish with live view in the center, you know the AF with your camera is the problem.
Then you test it on a different camera with center AF, to see if your camera and the lens is an unhappy combination, or the lens is problematic with every camera body.
This is how you isolate the problem.
That the lens has a curved focus plane it a totally different matter, and is inherent to a lens' design. So, when you get the lens to focus correctly in the center, it may well be that the corners on the same focal plane will be not in focus. This then is called field curvature. We think we are seeing field curvature and a big focus problem in combination, making the center defocussed, and the sides in focus.
Once you have established that the lens has an AF problem, you contact Nikon service and send a polite and clear description of the problem and your earlier visits with Nikon service centers, and some simple files that show when you focus with the center focus point, the amount of defocus.
If it gets sharper/ish with live view in the center, you know the AF with your camera is the problem.
Then you test it on a different camera with center AF, to see if your camera and the lens is an unhappy combination, or the lens is problematic with every camera body.
This is how you isolate the problem.
That the lens has a curved focus plane it a totally different matter, and is inherent to a lens' design. So, when you get the lens to focus correctly in the center, it may well be that the corners on the same focal plane will be not in focus. This then is called field curvature. We think we are seeing field curvature and a big focus problem in combination, making the center defocussed, and the sides in focus.
Once you have established that the lens has an AF problem, you contact Nikon service and send a polite and clear description of the problem and your earlier visits with Nikon service centers, and some simple files that show when you focus with the center focus point, the amount of defocus.