Wed 26-Dec-12 12:25 AM | edited Wed 26-Dec-12 12:29 AM by N80
You can't recoup fstops. One of the main reasons I want to upgrade from my D200 is low light performance. To maximize that will require a good sensor, a good processor/algorithm but still, and always, a wide aperture.....particularly if you include focus/tracking accuracy and a bright viewfinder.
All of which is to say, when the Sigma 50-150 f2.8 goes, it will have to be replaced by a 70-200 _f2.8_.......and a danged good one at that! Cha-ching!
And sure, with the D800's massive pixel count I can probably account for loss of effective focal length with cropping....to some extent. My Sigma 100-300 f4 will still probably be sufficient for motorsports and equestrian events, and will remain an excellent lens, but probably far less suitable for wildlife work on an FX body.
In any case, as you can see, I have tailored my lens stable for a really broad range of uses with the DX format. Even with additional pixels that stable will have to be reshuffled to retain that level of versatility. Not true with what we would expect of a D400 type body.
Fortunately I still have my primes: Nikkor 20mm f2.8, 35mm f2, 50mm f1.8 and 100mm f2.8 Micro-Nikkor and I prefer them at their "FX equivalent" focal lengths.