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.
GH4 test data on DxO Mark A65 test data on DxO MarkExcellent still image quality for its class; Fantastic, highly-detailed video quality; Superior video recording chops with 4K video (both Cinema 4K and Ultra HD); Responsive all-around performer with great AF performance and burst shooting; Rolling shutter is minimal with 60p and 30p video; Splash- and dust-proof magnesium alloy body; Built-in Wi-Fi with NFC.
High ISO performance not as good as some APS-C models (IQ drops quickly past ISO 3200); Overall still image quality not significantly better than the GH3; Sluggish buffer clearing with RAW files; Rolling shutter noticeable on 4K video; Not as compact as most mirrorless cameras.
