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.A7 test data on DxO Mark A55 test data on DxO Mark
Cameras with more dynamic range allow you to take photos with dramatic differences in highlight and shadow areas while retaining detail in both.
Think of a brilliant sunset on a rocky beach: Bright sunset in the background, with dark rocks in the foreground. High dynamic range means more of the extremes will be faithfully reproduced.
Dynamic range test data courtesy of DxO Mark.A7 test data on DxO Mark A55 test data on DxO Mark
Incredibly small body for a fully-featured, full-frame camera; Very high resolution; Hybrid autofocus is reasonably fast and confident; Significantly better burst-shooting performance than A7R; Excellent image quality even at very high sensitivities; Faster x-sync than A7R; Accepts existing Alpha-mount and E-mount lenses, and can optionally crop to APS-C image circle.
Grass-is-greener syndrome when compared to its higher-res sibling; Moderate performance; Loud shutter (but electronic first-curtain helps); Mediocre battery life when using electronic viewfinder; Weak low-light autofocus considering its price; Limited selection of native Sony FE lenses.