Since there's no easy automated way to keep up with changes on all the various Nikon Web sites, I periodically do a thorough perusal of the main sites. What struck me this time is that the bellows are gone. No more PB-6. Somewhere I missed its discontinuation.
With the emphasis and focus these days on consumer products and G lenses, we're slowly losing the ability to work real close. The close-up lens sets are gone. The few remaining extension tubes are all AI-compatible only. The bellows are gone. In essence, Nikon is saying to users "1 to 1 is all you'll get from us, and even there we haven't gotten around to updating all the macro lenses or providing you with a lot of different options."
So what's a serious macro afficionado to do? Fortunately, the high-end gear (D7000 and up) all still understands AI, so you could stock up on the remaining used macro gear pieces while they're still readily available. A more modern approach for some is to use Kenko extension tubes, I suppose. But things are getting trickier for macro users the further we get into the digital era. Canon users, by comparison, still have the 65mm MP-E that gets them to 5:1 (5x).
One of the things we lose as companies get hooked on volume is flexibility. Apple recently decided to discontinue its Xserve (rackmount OS-X server) because, as Steve Jobs put it "people weren't buying them." Nikon's doing the same thing with items in their lineup. But "not buying them" to these companies really means "the volume and profit are too low for us to pay attention to."
Thing is, the reason why we buy a DSLR is that it is part of a "system." Sure, most people buy a small subset of the items offered in the system, but the depth and breadth of the system is very important. It's one of the reasons why Sony has had a difficult time taking market share away from Nikon and Canon, for example: Sony's "system", partly lens offerings, but other things as well, is still weaker than that of the Big Two. If you allow your system to shrink to just the most popular items, you also make it easier for your competitors to get into the game.
Long ago (I think I first suggested this 14 years ago, and then elaborated on it a few years ago) I wrote that I felt that Nikon needed to seriously consider breaking their efforts apart into Consumer and Pro groups. As I noted, I'm quite willing to pay more (not a lot more, though!) for a deep, wide, well-supported, and thoroughly documented set of products. Consumers generally don't need that and are driven by price. But imaging pros need more than consumers. We're about to see a reminder of that in videography: Sony and Panasonic are driving many new large sensor video camera projects and systems forward to the light of day, and the "I'll use a DSLR because that's all there is that does the Hollywood look" user will likely migrate back to a dedicated video camera.
If you're not going to make all the deep and broad elements of a system, the other alternative is to openly and actively solicit other companies to fill the gaps. I'm sure there are third-party companies that would jump to make an automated bellows, automated extension tubes, and much more, but they aren't going to tackle that without some help from Nikon and some assurances that it'll remain viable for some period of time. Forcing everyone to reverse engineer all your protocols and tolerances is tantamount to "limiting the system." But the Japanese companies are bastions of NIH (not invented here) and like keeping a fortress around the information that would be needed by others to help make a better system.
Funny thing is, four or five serious system extender companies providing additional authorized F-mount, iTTL, and other extensions to the Nikon system would make Nikons even more compelling to the Canon user considering switching. Can you say "missed opportunity?"
You know, I watched Silicon Valley discover, tackle, and solve all the issues I've written about on this site regarding the camera companies (not every SV company solved every issue, obviously ;-). Sometimes I wonder if the Japanese companies have even discovered the problems yet, let alone tackle and solve them.
So, Nikon, in case you're reading this: I'm a dedicated pro and I have a job that requires me to get beyond 1:1. Exactly how do I go about that using Nikon equipment?
Update: some of you reading this have suggested the Novoflex bellows or the BR-2a reversing ring. In the case of the former, it's difficult to obtain in the US and, if I understand correctly, still is a mostly manual system. In the case of the latter, yes, that works if you have the right lens for the reproduction ratio you need. But it, too, will be a manual system. Nothing wrong with manual, of course, but it seems that we've allowed one aspect of photography to wither away and not get updated for the current digital and auto era. Curiously, Nikon does sell--through their Microscope division--the Naturescope Fabre Photo EX, which can provide high magnification using a DSLR (29:1 and up), but it isn't available in the US ;~). But even if it were available, it's that 1:1 through 5:1+ range that seems to have disappeared from Nikon's lineup.
Second Update: Nikon's answer is to use the the 105mm Micro-Nikkor AF-S and a TC-xxE to get to >1:1. Yes, that works. But it adds optics to the equation, and when I checked that with the older TC-20E, it wasn't good enough for me. True, I haven't checked it with the new TC-20E III, so I'll have to try that test later.