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.A7 II test data on DxO Mark X Vario test data on DxO Mark
Outstanding design and build; Exceptionally sharp 28-70mm equivalent zoom lens; Very good still image quality with accurate and realistic colors; Fairly speedy and accurate autofocusing.
Expensive, especially for a fixed-lens compact; Relatively slow f/3.5-6.4 lens; Below average video functionality and quality; Not at all pocketable, about as big and heavy as a mirrorless camera with a moderate zoom lens attached.
Excellent 5-axis sensor-shift image stabilization; Sensor-shift IS brings stabilization to nearly any lens; Much-improved ergonomics and top-deck control layout; 'Mark II' maintains same impressive image quality, dynamic range and high ISO performance; XAVC S 50Mbps video format; Faster start-up time; Hybrid AF performs well with good continuous AF.
(Similar to A7): Loud shutter (but electronic first-curtain helps); Battery life could be better; Low-light AF still not as good as most DSLRs; High ISO JPEGs look over-processed; Slow buffer clearing; Limited selection of native Sony FE lenses (but it's getting better).