Sony's best-selling APS-C mirrorless with exceptional autofocus and no-blackout burst.
The Sony Alpha A6400 was announced in January 2019, positioned between the A6300 and A6600 in Sony's APS-C mirrorless lineup. It brought the real-time tracking and real-time Eye AF algorithms — derived from the full-frame A9 — to the APS-C system, providing subject tracking performance substantially beyond earlier A6000-series bodies. The 180-degree flip-up touchscreen made it a popular choice for vlogging and self-facing video use alongside its stills capabilities.
The 24.2MP APS-C Exmor CMOS sensor pairs with the BIONZ X processor. The 425 phase-detection and 425 contrast-detection AF points cover 84% of the sensor area. At 11fps with AE/AF tracking the burst rate covers most sports and action subjects. 4K video records without pixel binning using full pixel readout, producing cleaner detail than binned alternatives. Battery life is rated at approximately 360 shots per charge using the NP-FW50 — moderate; a spare battery is advisable for extended shoots. At approximately 403g with battery and card the body is compact and light for APS-C mirrorless.
The A6400's real-time Eye AF and subject tracking are its defining practical characteristics: eye detection works reliably for portraiture in stills and video modes, and animal eye detection covers pets and wildlife. The 4K oversampled output is clean and suitable for social and documentary production. The 180-degree flip-up screen enables self-facing composition for vlogging. The NP-FW50 battery capacity is the primary operational constraint for all-day use. There is no IBIS — lens OSS or in-body stabilisation from a compatible gimbal is required for smooth video.
On the used market the A6400 is widely available and represents a strong APS-C mirrorless value. Battery management is the key operational consideration: plan for two NP-FW50 cells per shooting day. Condition checks: Eye AF tracking response in both stills and video, flip-up screen hinge, and both card slot contacts. The A6600 adds IBIS and larger battery at a higher price; the A6700 (2023) introduces a new sensor generation and significantly improved AF. Compatible with all Sony E-mount APS-C and full-frame lenses.