I bought my first macro lens in February 2008 - a Nikon 105VR F2.8. By most accounts, a very good lens.
It seemed fine at first, as I was just shooting test macro shots. Then I tried to use it to shoot some landscape shots, since it was on the camera and had about the focal length I wanted. When I
looked at the shots, I was stunned at how bad the corners were. It was as if they were coated with jelly.
This is the image that really got my attention.
This is a crop of the upper left corner.
Someone suggested perhaps there was a camera shake or VR issue, so I tried to eliminate those issues and perform a controlled test.
My opinion: This copy of this lens was defective, and I sent it back to B & H under warranty. (The replacement is fine). However, I did a block wall test before sending it back to see how bad
things were at different apertures.
The pictures were all shot in Aperture priority mode, on a good tripod (Bogen 3021) with a Really Right Stuff BH-55 ball head. The camera (D300) was set to use mirror lockup + 1 second delay to try
to eliminate any possibility of camera shake. I made 7 test shots, at apertures F2.8, 4.0, 5.6, 8, 10, 16 and 32. I shot in RAW, and used CaptureNX to convert to JPG with 'good balance' quality. No
sharpening was done (in-camera was set to +2). The results are below.
F2.8 image is above.
F4 image is above.
F5.6 image is above.
F8.0 image is above.
F10 image is above.
F16 image is above.
F32 image is above.