High ISO noise and shadow detail

The D800 offers ISO sensitivity up to 25,600 (equivalent) which, combined with a fast lens allows for shooting in very low light at hand-holdable shutter speeds. The default JPEG processing at these top ISOs is rather impressive, striking a reasonable balance between noise suppression and image detail. The camera is capable of noticeably superior results, however, when shot in Raw mode. As the examples below illustrate, processing a D800 raw file - even at ACR 6.7's default settings - allows you to effectively eliminate chroma noise while producing better-defined high and low-contrast edges compared to the in-camera JPEG at its default settings.

ISO 16,000 (equiv), in-camera JPEG at default NR and sharpening settings ACR 6.7 Raw at default NR and sharpening settings.

ISO 25,600 (Hi2)

Like its predecessor the D700, the D800's ISO sensitivity span tops out at ISO 25,600 (equivalent) - marked in the camera as 'Hi2'. While not a match for the D4's highest ISO sensitivity setting of 208,400 equiv, 25,600 is probably higher than most people will ever need to shoot. But what if you do need to go this high? Well, image quality at this setting isn't great, not surprisingly, but it's not awful either, and it's perfectly possible to draw results out of raw files which look more than acceptable even in extremely poor light. The image below was shot in a bar, using auto white balance mode, in light so low that the viewfinder image was almost indiscernible. But we'd still be confident in using the processed raw file for a small-ish print or web gallery.

ISO 25,600 (equiv), in-camera JPEG at default NR and sharpening settings ACR 6.7 Raw processed 'to taste'

Compared to Canon EOS 5D Mark III

On paper, the Nikon D800 has a resolution advantage over the 24MP Canon EOS 5D Mark III; one which you can explore for yourself in our studio comparison tool. We thought it would be interesting to see how these two cameras compare in terms of low light performance at an identical output image size. To that end we processed raw files from each camera with ACR's sharpening and noise reduction set to '0'. The 22MP Canon EOS 5D Mark III image was then upsampled to match the 36MP resolution of the D800. Identical amounts of low-radius sharpening were applied to both images in Photoshop.

The scene below was shot at ISO 6400 under low color-temperature (approx. 2600K) artificial light, designed to be representative of typical indoor lighting. This accentuates the appearance of noise due to the low level of blue light in the spectrum of the light source. This means that to achieve accurate white balance the blue channel has to be amplified strongly, and the green channel to a lesser extent - thereby increasing the visible noise. Each camera was used at its default noise reduction and sharpening settings.

Nikon D800
ISO 6400 1/30 sec., f/8.0
Canon EOS 5D Mark III
ISO 6400 1/30 sec., f/8.0
Upsampled to 36 MP using Bicubic

In looking at these files it is clear that precious little separates these cameras at ISO 6400 when their output size is equalized. To the extent that you can see any consistent differences, the upsampled Canon EOS 5D Mark III file looks slightly less-detailed - just as you'd expect. Yet this subtle difference could be minimized even further with a touch more sharpening applied to the Canon file in Photoshop. And its important not to lose sight of the fact that both of these cameras are performing extraordinarily well, showing fine detail with a level of chroma noise that is far from objectionable considering the ISO sensitivity and pixel count of both their sensors.