With noise reduction turned , images clean ISO 6400.Things breaking thereafter , noise creeping ISO 12,800 becoming obvious ISO 25,600 ISO 51,200.Even high ISO values though grain structure nice tight.If switch noise reduction , noise reduces expense detail.As camera could used confidence probably ISO 6400 , might little need switch correction on.ISO figure noise starts become visible : ISO3200 ISO figure noise overwhelms image : ISO12800 Interested ? Help support ePHOTOzine using links.Amazon UK Amazon US Nikon Z6 II Like Nikon Z6 , Z6 II offers great image quality , great handling , added `` oomph '' well convenience SD card slot.Noise low ISO50 way ISO1600/3200.Fine detail starts drop ISO3200 , continues go ISO6400.Noise becomes noticeable ISO12800 , ISO25600 .