Maximum effective ISO is an estimate of the highest sensitivity at which a camera can capture excellent quality photos.
Cameras with higher effective ISO will be better choices for indoor photography, night shooting, and indoor sports photography, especially if you intend to make large prints.
You can learn more at our glossary entry.
Maximum effective ISO test data courtesy of DxO Mark.D4S test data on DxO Mark SL (Typ 601) test data on DxO Mark
Cameras with longer battery life can take more photos before exhausting their batteries.
Excellent, tank-like build quality; First-rate ergonomics a pro would expect; Superb performance with confident autofocus; Great image quality; Big, bright viewfinder with 100% coverage; Excellent battery life; Doubles as a powerful video capture tool
Fairly minor upgrade over the D4; Image quality improvements apply only to JPEG; XQD card format isn't broadly accepted; Consumer-friendly default JPEG processing may turn off some pros; Body is large and hefty (but that's normal for pro gear)
Superb build quality; Amazing EVF; Great image quality from RAW files; Good high ISO performance; Very good dynamic range; Very low shutter lag; Fast AF on stationary objects; Class-leading ~11 fps burst mode; 4K DCI and UHD video; Full HD up to 120p. Built-in Wi-Fi and GPS; Dual card slots; Decent battery life for its class.
Big for a full-frame mirrorless camera; Very slow buffer clearing; Contrast-detect AF system struggles with moving subjects; In-camera JPEGs are muted and dull; Very limited native lens selection (but supports many other Leica lenses via adapters); Expensive.