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.A7S test data on DxO Mark RX100 II test data on DxO Mark
New, 20.2MP, 1-inch type, backside illuminated (BSI) image sensor produces superb image quality, with particular improvements in low light and high ISO; 3-inch tilting rear LCD screen handy for composing shots from difficult angles; Fast all-around performer with quick autofocus and virtually no shutter lag; New, multi-interface hotshoe for adding a strobe or optional electronic viewfinder; Built-in Wi-Fi with NFC.
Bigger and heavier than previous model; More expensive than previous model; Reduced burst performance when shooting RAW files; Somewhat confusing menu structure and control layout; Wi-Fi features can be difficult to set up.
Outstanding high ISO performance; excellent dynamic range; 4K video recording (via uncompressed HDMI); XAVC S option for HD video; Slightly improved battery life over A7/A7R; Built-in Wi-Fi & NFC connectivity.
4K video requires expensive external recorder; Sluggish startup time; Loud shutter; Silent Shooting mode hurts image quality; Lacks a built-in, pop-up flash; Limited selection of native Sony FE lenses.