Ray some good points there....
Well, thank you BJL
![Grin ;D](https://forum.luminous-landscape.com/Smileys/default/grin.gif)
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comparing at exactly equal focal length and then somewhat claiming a "victory" of higher pixel count for the camera with fewer, smaller, and in most respects lower quality pixels (ignoring the possible per pixel advantage of the larger photosites of the D800) seems a bit like choosing the rules to influence the outcome. With the bulk and cost of these cameras plus 400mm lenses, it would be little extra burden to use a TC to increase resolution from the D800 if needed, so exact equality of focal length seems overly rigid.
I wasn't claiming any
victory. This is what I wrote: "It would be
interesting to see a comparison between the 7D and the D800 in DX mode, both cameras using the same focal length of telephoto lens of equal quality."
I don't know what the outcome would be. I'm of the opinion that any increase in pixel count of less than 50%, is not worth getting too excited about. If one is comparing sensor performance, it's essential to have lenses of equal quality. If one is comparing lenses, it's essential to have sensors of equal quality and equal pixel count, at least if the methodology is similar to Photozone's.
Having determined, for example, that the D800 shot in DX mode is perhaps only very marginally less detailed than the 7D shot, using same focal length of lens of the same quality (whatever that focal length needs to be in order to achieve equal quality), one can then concentrate on the effects of differences in lens quality.
If one has a Canon 400mm that is actually sharper than the Nikon equivalent, then the matter is settled. The 7D with its
effectively longer lens,
actually greater pixel count, and
actually better lens, should produce a noticeably better result, with or without teleconverter.
On the other hand, if one has, or is prepared to buy, a 400mm Nikkor lens which is undeniably sharper than the Canon equivalent (if there exists such a lens), then this factor alone would probably offset any minor pixel-count advantage of the 7D, so it becomes a non-issue.
For myself, I have no interest in buying a very expensive and very heavy 400mm F2.8 prime. It wouldn't suit my purposes. I limit myself to the Canon 100-400/F5.6 IS. At 400m it's marginally sharper at F8 than at F5.6. I would like an upgrade that is sharper at F5.6.
When I use this lens at 400mm and F8, I usually have to be at ISO 400 or higher to get a sufficiently fast shutter speed. At ISO 400 and above, the DR advantage of the D800 pixel is greatly reduced.
Finally, it always seems a little strange when people make hypothetical comparisons between an actual available, thoroughly reviewed product from one company against speculated possible future improvements of another company in its product offerings. At the very least, do you care to speculate on what Sony and Nikon might be working on, and have to offer at about the same time as these imagined new Canon sensors arrive? Since you now own and use a mix of Canon amd Nikon gear, surely you can speculate about what both have under development?
Canon has a tradition of a significant time-lag between matching the pixel density of its full-frame cameras with that of its earlier cropped-format cameras. For example, we had to wait for the 1Ds2 to get the pixel density of the much earlier 6mp D60 and 10D models. We also had to wait a few years to get the 1Ds3 and 5D2 with a similar pixel density to the 8mp 20D and 30D.
Nikon are obviously aware of this history of Canon development. With the D800, Nikon have simply shortened that time lag and, in a sense, stolen a march on Canon.