Spent a bit of time playing with macro functionality today. Since I'm really just dipping my toes in macro work, I've never splurged on the latest greatest glass. The older micro-Nikkor lenses are plenty sharp, IMO: you give up convenience. But for somebody like me, who doesn't know if they'll stick with it, it makes a great deal of sense.
I picked up a pristine Nikkor 105/f4 non-AI (probably, what, about 40 years old) with a PN-1 extension from eBay for under $200; had it converted to AI compatible for another $35. I don't have VR; I have only manual focusing, which is what most do in macro work anyhow. Neither of these are big deals when you use a tripod or monopod.
If I use the lens without the PN-1, I get rangefinder focusing - that is, the camera tells me when focus is locked on. However, when I put the PN-1 in the equation, I lose that. I'd have to upgrade to the PN-11 tube, I think.
Anyhow: the big drawback is LiveView / ViewFinder only shows me the amount of light the aperture I have selected is admitting, tube or not. So, my standard approach is to open to f4; try to guess at the center focus point - then crank the aperture down to f32 to get at least some DOF, but shoot basically blind.
The D7100 LV screen is a bit better for reading focus than the D7000.
First image was taken without the extension tube.
Click to enlarge.
Second image is the same feather as in the first image, however, the PN-1 tube was added, and we're at 1:1 - it filled the viewfinder. I used LiveView to focus in the center spine and get that as sharp as possible at F4, then cranked to f32 and shot.