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 K-30 test data on DxO Mark
Pentaprism viewfinder is bright and accurate; Weather-sealed body can handle direct rain; Twin control dials make exposure control a snap; Solid build; Great image quality.
Lower resolution than some rivals; Not as small as recent Pentax entry-level and mid-range models; A couple of ergonomic and UI quirks; Shutter isn't the quietest; 18-55 kit lens isn't weather-sealed.
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.