This is a test of the camera's noise levels. The higher the signal to noise ratio, the greater the difference in strength between the real image data and random background noise, so the 'cleaner' the image will look. The higher the signal to noise ratio, the better.
Sony A7R II signal to noise ratio charts
JPEG signal to noise ratio analysis: The A7R II's in-camera image processing does a good job of controlling noise, enabling the camera to turn out an excellent set of results.
Raw (converted to TIFF) signal to noise ratio analysis: The A7R II competes well with the Canon and Nikon cameras, with noise kept well hidden for much of the sensitivity range.
Sample Sony A7R II ISO test results
The signal to noise ratio charts use laboratory test equipment, but we also shoot a real-world scene to get a visual indication of the camera's noise levels across the ISO range. The right side of the scene is darkened deliberately because this makes noise more obvious.
ISO 200: Click here for a larger version.
ISO 6400: Click here for a larger version.