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.E-P5 test data on DxO Mark E-M1 test data on DxO Mark
Handsome retro styling; Very good image quality and dynamic range, with competitive high ISO performance; Lightning fast autofocusing; Excellent burst speeds (nearly 10fps at full res); Top shutter speed of 1/8000 second; Sharp, bright 17mm f/1.8 kit lens; 3-inch tilting touchscreen LCD with 1.04M dots of resolution.
Heavier than some mirrorless models; Weak flash; Below average battery life; No built-in viewfinder (but EVF available in a kit or for separate purchase); A bit pricey compared to the similar E-M5, which offers a built-in EVF and weather sealing at about the same price.
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.