At lowest ISO setting ISO50 , dynamic range reduced.Noise performance good ISO100 ISO6400 noise starts appear.ISO25600 likely highest ISO setting 'll want use without applying processing images , noise becomes much stronger ISO51200 , setting 're best resizing image converting black white ( ) .The ISO speed goes ISO102400 , setting best avoided.Noise performance similar Canon EOS 5D Mark III , although , higher ISO settings , including ISO25600 , less chroma noise ( coloured patches colour ) 5D Mark IV images.Processing 5D Mark III raw images latest version Adobe Camera Raw likely get equally good results.Noise performance ISO25600 better 36-megapixel Nikon D810 , Pentax K-1 , similar 42-megapixel Sony A7R Mark II ( goes show benefits BSI CMOS sensors ) .Noise reduction options : Off , Low , Standard , High , 're shooting JPEG , Multi-shot Noise Reduction option .