Very interesting and informational review.
Many of the discussed points apply not only to Nikon cameras, but also to other FX and DX models, especially the diffraction issue and "bigger crop" trap.
Thanks Les for the link to Thom Hogan's review. I find it a very balanced review on the whole, but not without flaws. I'm very puzzled by the following statement from that review.
I'm finding a lot of folk picking up the D800 models fall into the Big Croppers group: they're buying a D800 because it allows them to crop dramatically. As in pulling out 12mp pieces from a 36mp source. I'm not sure why these folk think that's any different than owning a D7000. If you're always cropping that much, the D7000 is actually slightly better than the D800 in terms of pixel density (very slightly: 16mp DX on the D7000 versus 15mp DX on the D800), plus you'll save enough money to buy some lenses that'll let you crop less.
This seems a very confused statement to me. I think Thom's put his foot in it here. He hasn't thought it through. Maybe he's just getting old, as many of us are, so please don't anybody think there are any hard feelings in the following comments. I make them purely for the sake of clarity.
(1) The difference between a 15mp and 16mp cropped-format camera is very trivial. I'd describe it as less
than the resolution difference between the Canon 40D and 50D at F16, and less
than the resolution difference between the D3X and D800 at F16.
(2) Any FX lens attached to a D800 becomes a much more valuable and flexible lens
than it does attached to a D7000, whatever the quality and focal length of the lens.
I own just two Nikkor lenses, the 14-24/F2.8 and the 24-120/F4 zooms. On the D7000, these two lenses become effectively a 21-36/F2.8 and a 36-180/F4 (in terms of 35mm format FoV). However, in terms of FoV at both the equivalent image quality and sometimes even better image quality, by the D7000 standards, these lenses when attached to the D800 effectively become a 14-36/F2.8 and a 24-180/F4. For example, when a 24mm shot from the D800 is downsampled to an equivalent 16mm shot from the D7000, same FoV, the D800 shot is a better quality image, without doubt.
In other words, I'm getting the best of both worlds; the wider angle advantage of the larger format, plus the longer reach of the cropped format.
So what happens in the case of someone who always
uses telephoto lenses for birding, and is not interested in the wide-angle aspect of full-frame? Let's consider two photographers out shooting with their sharpest lens, a 400/F2.8 monster which is necessarily a prime if it's the best lens available. One photographer has a D7000, the other has a D800. Both these lenses on the D7000 are effectively 600mm, as they are on the D800 in DX mode. (Okay! On the D800 not quite 600mm; only 581mm. Big deal!)
The point that Thom seems to have missed is that the D800 user effectively has a 400-581/F2.8 zoom, with just one prime lens. Not only that, it's a zoom that has the specifications of a high quality prime lens at all focal lengths between 400mm and 581mm (at least in the central area). It's a zoom lens without precedence. No amount of money could buy such a lens.
Nevertheless, I don't wish to imply that Thom's advice here is not without some
merit. If you really are
only interested in getting the longest reach with your Nikkor telephoto lenses, then a 24mp D3200 might be a better option than a D800, provided
you are not too fussed about SNR and DR.
It so happens that DXOMark have now published their test results for the D3200. It's very clear that the D3200 images, at equal print size, downsampling the 24mp to 16mp, will be noisier and will have lower DR than the D7000 images.
If one wishes to crop the D3200 image to extend the telephoto reach beyond that of the D7000, ie, compare equal size but unequal
FoV images, the differences in SNR and DR will be even greater. We're looking at differences in SNR, at 18% grey, of 1/2 to 2/3rds of a stop worse compared with the D7000 and D800E, and differences in DR of up to one stop worse, and even greater. At ISO 200 the DR of the D800E pixel is over
one stop better than the D3200 pixel. That's significant. Even at ISO 6400, in case you want a really fast shutter speed to catch that lizard catching a fly, the D800E pixel has almost one full stop better DR than the D3200 pixel.
Sorry, Thom, but the truth must prevail.