Emergency use situations image better image.Overall though , satisfactory ISO performance.ISO figure noise starts become visible : ISO12800 ISO figure noise overwhelms image : ISO25600 Interested ? Help support ePHOTOzine using links.Amazon UK Amazon US Canon EOS R5 The Canon EOS R5 great full-frame mirrorless camera , high-resolution sensor , excellent electronic viewfinder , rapid focus fast continuous shooting.Noise low detail highest lowest ISO speeds.Noise starts appear ISO3200 , fine detail starts drop , continuing go ISO range.Images still usable ISO speeds ISO12800 ISO25600 depending needs.ISO51200 shows highest levels noise , lowest levels detail , speed best avoided unless choice use speed.ISO102400 also best avoided , although 's worth noting colour saturation remains quite good .