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.K-30 test data on DxO Mark E-M1 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.
Exceptional rugged, weather-proof, professional build; Lightning fast contrast-detect AF, and phase-detect AF that makes Four Thirds lenses far more responsive; Tons of useful physical controls with immense customizability; Arguably the best image quality of any Micro Four Thirds camera we've tested to date; Large, sharp, high-resolution electronic viewfinder; Advanced Wi-Fi capabilities, including remote control shooting in PASM exposure modes.
Bigger and heavier than many other compact system cameras; Most expensive Micro Four Thirds camera on the market to date; Menu system and customization options have a steep learning curve; No optical low-pass filter means greater risk of moire; No built-in flash.