Sony's camera that made full-frame mirrorless mainstream — 24.2MP, 693-point AF, outstanding value.
The Sony Alpha A7 III was released in February 2018 as the third-generation A7 standard model, incorporating the A9's 693-point phase-detection AF system and BSI Exmor R sensor architecture in a mainstream full-frame body. 5-axis IBIS provides approximately 5 stops of stabilisation. 4K/24p records from the full sensor width; 4K/30p applies a 1.2x crop. At approximately 650g the A7 III defined the practical specification baseline for full-frame mirrorless in its generation.
The 24.2MP full-frame BSI Exmor R CMOS sensor pairs with the BIONZ X processor. The AF system provides 693 phase-detection points covering approximately 93% of the sensor area with Real-time tracking. Burst shooting runs at 10fps. 4K/24p uses full sensor readout; 4K/30p applies a 1.2x Super35 crop. 5-axis IBIS. Battery life approximately 710 shots via rear LCD using the NP-FZ100, body weight approximately 650g with battery and card, dual SD card slots (slot 1: UHS-II; slot 2: UHS-I only).
The A7 III's 693-point PDAF system — derived from the A9 — was the significant upgrade over the A7 II's hybrid contrast/phase system, enabling effective continuous subject tracking for sports and wildlife rather than only static subjects. BSI sensor architecture improved high-ISO performance over the frontside-illuminated A7 II sensor. 5-axis IBIS extended handheld capability at slow shutter speeds. The A7 III established what became the standard expectation for full-frame mirrorless: PDAF tracking, BSI sensor, IBIS, and 4K video at a mainstream price.
On the used market the A7 III is available at accessible full-frame mirrorless pricing. The A7 IV (2021) upgraded to 33MP, 759-point PDAF, and 10-bit 4:2:2 internal video. Condition checks: IBIS operation, both SD slot contacts — note slot 2 is UHS-I limited, not UHS-II — NP-FZ100 battery health (shared across the Sony FE full-frame lineup), and weather sealing at port covers. Compatible with all Sony FE-mount full-frame and APS-C E-mount lenses.