We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using DXO Analyzer software to generate the data to produce the graphs below.
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
JPEG signal to noise ratio
These results show that Canon and Nikon have a similar aim for the in-camera processing of their top-end cameras. This indicates that the JPEG files from the Canon 1DX, Canon 5D Mark III and Nikon D4 have very similar noise levels. Not surprisingly, these camera beat both the older Canon 1D Mark IV and the high-resolution Nikon D800.
Raw (after conversion to TIFF) signal to noise ratio
It's a very similar story for the raw files (after conversion to TIFF), though the Canon 1DX appears to have a significantly better result at the highest sensitivity settings.
JPEG dynamic range
Whereas the Nikon D4 and D800 produces JPEGs with a dynamic range of around 11EV at the lower native sensitivity settings, the Canon 1DX and 5D Mark III produce results closer to 10EV. However, the Canon 1DX does a better job of maintaining the dynamic range as sensitivity rises.
Raw (after conversion to TIFF) dynamic range
With the exception of the Canon 1DX, all the cameras' raw files (after conversion to TIFF) have significantly higher dynamic range than their JPEG output. This means that there is more scope to adjust the raw files to reveal tonal variations in the shadows and/or highlights.
Although the D800 is capable of capturing the greatest dynamic range, at the mid-range sensitivity settings, the 1DX is best. At the highest settings, the Nikon D4 and 1DX lead the way, with the 1DX doing the best job at the very top value.