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.EOS M test data on DxO Mark GM1 test data on DxO Mark
Excellent image quality similar to Rebel T4i, T5i and SL1 DSLRs, with 18-megapixel APS-C-type sensor delivering considerable resolution for a mirrorless camera; Solid build and sleek design; Bright, high-resolution 3-inch LCD touchscreen monitor; Full 1080p HD video recording that's virtually silent with an STM lens.
Barely acceptable autofocus speed still lags far behind most mirrorless cameras despite firmware update fix; Limited physical controls and buttons, including no Program, Priority, or Manual on Mode dial; Lacks built-in flash or electronic viewfinder option; Only two compact EF-M mount lenses currently available.
Large Four Thirds sensor is impressive for a camera this small; Shares sensor and processor of GX7; Excellent image quality with class-leading high ISO performance; Responsive all-around performer; AF system is fast and accurate; Easy to use and responsive touchscreen; Built-in Wi-Fi with remote control and sharing features; Lightweight and pocketable design makes it easy to carry everywhere.
Can be awkward to use with larger lenses; Rear dial is easy to accidentally press; Lacks a hot-shoe for EVF or external flash; Weak built-in flash; 1/50s flash sync; No 1080p60 video; No external headphone jack or mic input.