Nikon D3X RAW Image Quality
We've recently started looking at RAW files converted with dcraw, an excellent freeware raw converter. dcraw usually offers timely support for the latest cameras, but more importantly, it does not apply any noise-reduction, sharpening or other corrections such as geometric distortion correction to the output files. (We found that Adobe Camera Raw still applies some limited noise-reduction when its NR settings are set to zero, and it also applies other corrections depending on the make and model of the camera). There will always be differences between RAW converters, in terms of the sort of de-mosaicing algorithms they use (the processes by which they convert the separate Red, Green, and Blue data sets to an array of full-color RGB pixels), but dcraw seems to use a fairly generic algorithm that delivers good sharpness with relatively few artifacts, and can be counted on to not apply any noise reduction if you don't want it to. (That said, looking at the ISO 25,600 example from the 5D Mark II below, it's clear that dcraw's de-mosaicing approach does have some tendency to produce rectilinear artifacts in response to high noise levels.)
Below are crops from Nikon D3X RAW files compared to RAW files from other 21+ megapixel digital SLRs, converted with dcraw.
The crops above compare the Nikon D3X RAW noise performance to that of the Canon 5D Mark II, Canon 1Ds Mark III, and Sony A900, across their entire ISO ranges. Noise levels from the four cameras are pretty similar up to and including ISO 400. At ISO 800, we see the two Canons and the Nikon pull away from the Sony by just a hair. At ISO 1600 and above, the Sony appears to be behind the others by roughly a full stop in terms of noise, but the other three are closely matched. At ISO 6,400, the 5D Mark II seems to slightly outperform the D3x, but it's very, very close.
A lot of our readers no doubt are wondering how the D3X, 5D Mark II and Sony A900 compare to the D3. Below are crops comparing high ISO RAW files, resized to the D3's image size using Photoshop's Bicubic interpolation. (The Sony A900's high ISO noise reduction was set to Off; the rest of the cameras do not apply noise reduction to RAW files by default.)
In the crops above, it's clear that the Nikon D3 is still the high ISO noise champ (as well as the D700, as they share the same sensor), but the added resolution of the higher megapixel cameras is readily evident even after resizing down to the D3's image dimensions, at least at lower ISOs.