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-M1 II test data on DxO Mark RX10 III test data on DxO Mark
Versatile all-in-one replacement for a DSLR or mirrorless camera; Great handling and build; Excellent image quality; Spectacular zoom reach; Swift performance with generous buffer depths; Extremely capable video capture; Comprehensive remote control; Quick-and-easy image sharing
Extremely expensive for a fixed-lens camera; Fairly heavy for fixed-lens camera; Somewhat soft in the corners at wide-angle or tele; Noise reduction intrudes at higher sensitivities; No built-in ND filter; Not as fast when shooting raws; Slow buffer clearing
Excellent image quality; Very good dynamic range & high ISO performance; Fantastic C-AF performance; Incredible burst rates, even with RAW; 4K UHD & Cinema 4K (DCI) video; Clean HDMI; Dual SD card slots.
Expensive; Menus still confusing; UHS-II support only on one card slot; No optical low-pass filter means greater risk of moire; No built-in flash.