The a9 is Sony's flagship full-frame mirrorless camera that is targeted at professional, action and sports photographers.
It might use a 24.2-megapixel full-frame image sensor that is of a lower pixel count than the 42.2-megapixel one in the a7R II. But the a9's image sensor uses a stacked design.
This stacked design has the processing circuit and integral memory located just behind the image sensor's pixel area to deliver data to the Bionz X image-processing engine at 20 times the speed of the a7R II.
This enables the a9 to shoot at 20 frames per second (fps) without blackouts. In other words, you get an uninterrupted live view of the subject on the electronic viewfinder at this maximum burst speed. The camera can also deliver up to 60 autofocusing (AF)/automatic exposure (AE) calculations per second.
Furthermore, the a9 packs a whopping 693 phase-detection AF points, covering around 93 per cent of the frame, compared with the already-stellar 399 AF points in the a7R II.
Design-wise, the a9 looks like the a7 series at first glance. But there are several design improvements in the a9.
There are now a lot more buttons and dials that give you direct control. Near the rear thumb rest, there are dedicated AF-On, AE-Lock buttons and an AF mini-joystick that lets you move the AF points easily. This mini-joystick can also be used to navigate the camera's menu.
PRICE: $6,299 (body only); $10,198 (with FE 70-200mm f/2.8 GM OSS lens)
IMAGE SENSOR: 24.2-megapixel full-frame Exmor CMOS
SCREEN: 3-inch tiltable touchscreen LCD with 1,440,000 dots; electronic viewfinder with 3,686,400 dots
SENSITIVITY: ISO 50 to 204,800
SHOOTING SPEED: Up to 20 frames per second
CONNECTIVITY: Wi-Fi, Near Field Communication and Ethernet
WEIGHT: 673g (body only, with battery and memory card)
BATTERY LIFE: 4/5
VALUE FOR MONEY: 4/5
A shooting drive mode dial - sited on the camera's top left - lets you quickly toggle through the shooting speed. Sitting below this dial is an AF mode selector that lets you switch from single AF to continuous AF or manual focus. All these new buttons and dials make handling the camera a joy.
On the side of the grip, there is a compartment for dual SD card slots. But only one slot supports the faster UHS-II format.
The left side houses plenty of ports, including an Ethernet port for quick uploading of photos to your computers, and a micro-USB port for charging.
For this review, I used the a9 predominantly with Sony's new FE 70-200mm f/2.8 GM OSS lens, but switched to the Sony FE 24-70mm f/4 GM lens sometimes for landscape shots.
The a9's body features a magnesium-alloy construction with weather-resistant sealings, but it is slightly bigger than its predecessors. Its rubber grip offers a great grasp of the camera.
With the 24-70mm f/4 lens, the balance felt right. But when fixed with the telephoto 70-200mm f/2.8 lens, it felt a tad front-heavy. I would recommend getting the optional VG-C3EM battery grip ($499) if you intend to use telephoto lenses extensively.
Operation-wise, this is a very responsive camera. The a9 takes 1.5sec for both start-up and shutdown, compared with the usual 2sec of its competitors.
On paper, the a9 has a shooting buffer for 241 RAW images or 362 Jpeg images. In my tests using a UHS-II SD card with a writing speed rated at 299MB per second, it was able to shoot 253 RAW images in 13.4sec before the buffer was full.
This stunning performance puts many DSLR cameras to shame. And when it comes to AF speed, the performance was equally jaw-dropping.
In bright sunlight, the AF was instantaneous in locking onto a focus. Even in dim lighting conditions, the camera took only 0.5sec to secure a focus with the help of the AF assist light.
With the lack of blackout and the lightning-quick AF, I was able to track and capture fast-flying birds like kingfishers and olive-backed sunbirds in action with ease. Furthermore, the shutter speed can be as fast as 1/32,000sec, ensuring that even the quick flapping wings of the sunbird are captured in sharp focus.
Image quality is simply superb. Images are sharp and display great dynamic range with plenty of details, even in darker areas.
Noise performance is excellent too. There were very few noise artefacts even at ISO 6,400. At ISO 12,800, noise artefacts were more evident but the detail loss was minimal. I have no qualms shooting events at this sensitivity.
Even at ISO 25,600, I think it is still good enough for small prints and Web use. I would not recommend anything at ISO 51,200 and above, as the detail loss becomes really evident and discolouration becomes visible.
Battery life is much better than its predecessors'. The a9 can shoot around 650 still images on a full charge, while its predecessors usually managed only around 350.
• Verdict: Simply put, the Sony a9 is a very strong contender for camera of the year. With its speed and accuracy, it is an extraordinary camera that is suitable for any kind of photographer, be it sports or wedding.