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 K-01 test data on DxO Mark
Very good image quality and excellent high ISO performance. Premium build quality. In-body image stabilization. Lots of creative features. Full HD movie capture with manual exposure control.
Barely any smaller than a standard SLR, but lacks viewfinder and phase-detect autofocus. Contrast-detect AF is slow and unreliable. Body design is clumsy and uncomfortable. Very slow raw burst shooting.
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.