The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications).
In our tests we found that measured ISOs from the Nikon D800 match the marked ISOs within 1/6 stop accuracy, meaning ISO 100 indicated = ISO 100 measured.
Noise and Noise Reduction (JPEG)
Note: this page features our new interactive noise comparison widget. By default, we show you the default noise reduction settings of the camera tested, and three other models of the same class. You can select from all available NR options, and from other cameras. The 'tricolor' patches beneath the familiar gray/black/portrait images are taken from the same test chart, and show how noise impacts upon blue, green and red areas of a scene.
ISO range noise comparison
Note: With the Pentax 645D you can specify the minimum ISO at which NR adjustments will be applied. Here we have specified ISO 200 as a starting point for all of the files from this camera.
The D800's default noise reduction setting does a very impressive job of controlling chroma and luminance noise in camera-generated JPEGs. Noise levels are largely consistent with image samples from lower pixel-count cameras such as the Nikon D4 and Canon 5D Mark III, with any differences you can discern being almost pointlessly minor up to ISO 3200. We're very impressed overall with the noise performance Nikon has achieved with a 36MP sensor. You can see a real world comparison between the D800 and the Canon EOS 5D Mark III on our high ISO noise comparison page.
Looking at the graph, the D800 and Pentax 645D appear to achieve almost identical levels of chroma noise reduction. The samples give a more complete picture, however, as the 645D displays more artifacts at every ISO setting.
As you can see on our photographic tests page, noise performance from the D800 is largely on par with that of the 12MP D700; a very impressive feat.
Raw noise (ACR 6.7 beta, noise reduction set to zero)
The Raw files give a clear picture as to the amount of noise suppression being applied to the D800 JPEGs we saw above. Even with more visible noise, however, mage detail is impressively well-preserved up through ISO 1600. You'd be hard pressed to find significant differences in detail between the D800 and its lower-pixel-count rivals. At ISO sensitivities of 3200 and 6400, the D800's noise pattern obscures some fine detail, but the files are still eminently usable for both print and online viewing. At its highest ISO sensitivities, chroma noise becomes prominent and image detail is significantly reduced, with ISO 25600 best suited for small prints.
Looking at the graph, you can see just how closely the D800 competes with its full frame and medium format rivals in both chroma and luminance noise.