At ISO6400 's another slight drop fine detail.At ISO12800 's noticeable drop fine detail , noise increases.At ISO25600 noise smoothed quite lot detail lost.ISO51200 shows noise , colour saturation remains reasonable.You might want avoid using speed , unless absolutely necessary.ISO102400 ( Hi1 ) shows lot noise.ISO204800 ( Hi2 ) gives worst result , camera unable effectively reduce chroma noise ( colour splotches ) .As shots , found could get better results processing raw files adjusting noise reduction settings tastes.ISO figure noise starts become visible : ISO6400 ISO figure noise overwhelms image : ISO102400 Interested ? Help support ePHOTOzine using links.Amazon UK Amazon US Sigma fpL Like Sigma fp , fp L , maybe slightly odd choice , others , feel like great option , particularly videographers.Noise well controlled , remains low , good levels detail , ISO3200 , detail starts drop .