Sony's groundbreaking stacked-sensor sports camera, the first mirrorless to challenge pro DSLRs.
The Sony Alpha A9 was announced in April 2017 as the first Sony mirrorless body with a full-frame stacked CMOS sensor, enabling 20fps continuous shooting with full AF/AE tracking and a completely silent electronic shutter at full speed — capabilities that no full-frame mirrorless camera had achieved before it. The 693-point phase-detection AF covering 93% of the frame set a new benchmark for mirrorless tracking at the time. 4K video records from oversampled full-frame readout.
The 24MP full-frame stacked Exmor RS CMOS provides fast readout for electronic shutter operation. The 693-point phase-detection AF covers 93% of the frame with continuous subject tracking at 20fps. Electronic shutter burst runs at 20fps; mechanical shutter at 10fps. 4K video records at up to 30fps. Dust and moisture sealing is built in. Battery life approximately 650 shots using the NP-FZ100, body weight approximately 673g with battery and card, dual SD/SDHC/SDXC card slots.
The A9's practical significance was establishing that mirrorless could match professional DSLR tracking at 20fps: a combination that only Nikon D5 and Canon 1D X Mark II DSLRs could match at the time, and only with mechanical shutters. The silent electronic shutter at 20fps is the defining feature for ceremonies, concerts, and sports venues where mechanical shutter noise is unacceptable. The A9 II (2019) refined the tracking algorithms and added anti-flicker shooting without changing the core sensor or speed.
On the used market the original A9 is available at lower prices than the A9 II. Condition checks: electronic shutter operation, both SD slot contacts, weather sealing at body seams, and NP-FZ100 battery health. The NP-FZ100 battery is shared across the A9 II, A7R IV, A7S III, A7 IV, and A6700 — spares and accessories are broadly available. Compatible with all Sony FE-mount full-frame and APS-C E-mount lenses.