Like I said, I knew I wasn't crazy (or maybe any crazier than friends already thought). Ever since I bought a Nikkor 18 - 200mm lens several years ago I've thought it had a focus problem. This morning I finally decided to do something about it. I'd gotten a
Spyder Lenscal (tm) device from B&H last summer, but have been too busy with other things to set it up and see what the focus was on the lens. What a dope. I could have saved myself a lot of fighting with images. After completing the AF Fine Tune adjustment on my Nikon D300 I had to try "something" that wasn't a Lenscal target. I was sitting in the office and looked around for anything I could sample to check focus. I popped up the flash and shot the little Logitech webcam on top of the monitor. It was good as anything else that was "up close". The lens was racked out to 200mm. Flash on TTL (hence the highlight). The top shot was with the settings I thought gave the best focus. I was shooting tethered, using Adobe Photoshop Lightroom 4 (LR4), so I had two images I could instantly study. One on each screen. One, the whole image and the other a magnified view. The "adjusted" focus looked pretty good, but pretty good compared to what? To find out, hit the "Read More".
I didn't move anything but the camera. I took it down from my eye, moved the AF Fine Tune point back to zero and took another shot. Set LR4 to do a comparison view and looked at two samples. Click on the image to get a larger view to see for yourself. The printing on the bottom shot is much softer than the same printing on the top shot. Eureka, I was right all along.
If you have a camera capable of doing AF Fine Tune adjustments, you might want to look into a Spyder Lenscal device. For Nikons, think one digit or three digit designations (D3, D4, D300, D600, D800). I'm pretty sure (from what I've seen in the forums on the net) AF Fine Tune isn't available on two and four digit Nikons (D80, D90, D3200, D5000, D7000).
Nikon is a manufacturing company, not really a photography company. They manufacture photographic (and other) products. Photography companies use the products made by Nikon (and others). As such, as a manufacturing company, Nikon makes products to specific tolerances. You have to remember that a DSLR is a two part system. The camera body and a lens. Both have tolerances. It is possible to get two components that are on the far sides of acceptable tolerances. If that's the case, you can wind up with a pairing that's out of acceptable limits and, in my case, a combination that gives a softer than typical image. I'd say mine was the luck of the draw.
I've been able to get acceptable images out of the 18 - 200mm zoom, but they came with a price. I had to do a lot of fighting to make them sharp. I'll be doing some real world testing with the new setup this weekend. I'll let you know how I make out.