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.G1X test data on DxO Mark G1X Mark II test data on DxO Mark
Large-sensor image quality. Sharp lens with useful zoom range. Tilt/swivel LCD. Twin dials. Smaller than competing interchangeable-lens cameras with a similar lens. Lots of photographer-friendly features.
Not as small as you might hope. Mediocre burst shooting and autofocus speed. Far too easy to accidentally change exposure compensation. Viewfinder is of surprisingly little use. Battery life could be better.
Wider, longer, faster lens than predecessor, with good overall optical quality; Faster AF performance; Closer macro shooting; Built-in Wi-Fi and NFC with remote shooting; Decent JPEG burst performance; Excellent build quality.
Localized flare issue when wide open; No real net improvement in image quality over predecessor; Slow burst mode when shooting RAW files; Poor battery life; Video quality is so-so (not like Canon DSLRs).