I agree the D600 and D4 (and the D800) are of course "better" than the old D300/D300s. For most purposes they are WAY better. But for long lens bird photography, the current newest Nikon bodies are frustrating and fall short of what we all know is possible at this point. It's not just a "price hole" in Nikon's line up. It's a set of features that is possible but not yet offered. Briefly, I'll list the most important features and I'll add price:
- DX format sensor with resolution in the range of 20-24 megapixels and the highest possible quality
- Best possible high ISO noise reduction
- Continuous burst frame rate of 9fps or better
- Professional magnesium/sealed body that mates well with heavy professional telephoto lenses
- $1600-2000 ?
Of course there are other important features, but the list above encapsulates the essentials. I agree that Nikon may come closer to supporting this niche with a rumored upcoming D7100. I'm
not sure the feature set above will be accommodated within the FX format using "crop modes." Maybe someday, but I don't see it yet in the $3000 D800, which is a wonderful camera and admittedly "significantly better" for bird photography than my old D300.
Fortunately, I think sports photographers desire a similar set of features, and that gives me hope that eventually Nikon will satisfy me. There are a lot more professional sports photographers than bird photographers.
I think the earthquake and tsunami in Japan probably slowed Nikon way down for a while. They've obviously doubled down in the race to full frame, and they've done a great job in that. They must be aware that sports/wildlife photographers want a pro DX body. Others have suggested a mirrorless DX body may be just around the corner, and since the "Nikon 1"/CX mirrorless format is already out there supporting the mass consumer market, hopefully a new DX mirrorless body would be targeted to more serious photographers and compete with other serious APS-C camera bodies like the Fuji X-Pro1 and new X-E1. That really makes sense and would be very interesting.
But for now, I just tell myself it's great that the camera I want doesn't exist, since I don't want to spend more money right now anyway! And the longer it takes, the better the upgrade will be!
--Dave B