We have arranged some HIGH ISO samples of all the flagship full-frame DSLR, as we all know that Nikon D4 and DF shares same sensor so the overall image quality of both the camera is almost same, but at ISO 51200 the Nikon DF image is showing bit more color noise compared to D4. Canon 1DX is also showing very good image quality during HIGH ISO test.
Also see – Nikon DF High ISO Test
image credit – focus-numerique