Nikon D800, 36 Megapixels and Blur

[Kayaker72]

Ok it’s a Nikon flame, I am still waiting on Canon’s response to this new 36mp camera

Yep...but it made me laugh.....

[Daniel Browning]

At a certain point the noise issue will bite you at too high a resolution and too low light level.

Theoretically, that's true -- and it's a good point to bring up. However, in practice, DSLR manufacturers have had a very hard time bringing the low light advantage to market for big pixels (D3S was one exception). As of right now, most of the 2-micron pixels (e.g. digicam) have 3 times less read noise than most of the 6-micron pixels (DSLR), giving the same noise floor after integration. But even if they fix whatever that problem is in the next generation, the difference is only going to affect people who shoot very high ISO (which is a large percentage of online forum users, but a very low percentage of photographers overall). The majority of photographers are already limited by photon shot noise only -- which so far has remained the same for a huge variety of pixel sizes, thanks to microlenses. (Not counting the effects of OLPF, sharpening, and subjective perception -- all of which favor smaller pixels as it pertains to noise if and when they come into play.)

[Daniel Browning]

Why would blur be much more obvious[?]

It wouldn't -- unless you assume (as Nikon apparently did for this article) that the viewing conditions are such that low-resolutions (less than 36 MP) cannot take full advantage of the display. If they had instead assumed all their users were only displaying uncropped images on HD projectors and 4x6 prints, then the PDF would have been a lot smaller.

[Daniel Browning]

[...]I started wondering if I would see much difference due to pixel size when using the 100-400 on a 5Dii and comparing shots to the 70-200 IS ii on a 7D which has slightly smaller pixels than the D800.

The way your test is setup mixes the effect of sensor+lens size with pixel size. For example, if you had tried the 20D+70mm vs 5D2+112mm, you would find the 5D2 far superior, even though the pixel size is the same. That is because of the benefits of sensor size (especially if f-number is kept constant).