Sony A9

The Sony Alpha A9 is a professional 24.2 Megapixel full-frame mirrorless camera, aimed at professional sports photographers. Announced in April 2017, it features the first full-frame stacked CMOS sensor which includes integrated memory and 20 times faster data readout compared to previous full-frame sensors. This allows the A9 to shoot at 20fps with autofocus for up to 241 RAW files or 362 JPEG images.

The A9 employs a fully electronic shutter to allow fast, silent and vibration-free shooting, shutter speeds up to 1/32000, and electronic composition with no blackout. Meanwhile faster speeds allow the A9 to deploy an anti-distortion shutter which claims to eliminate rolling shutter artefacts which have previously plagued electronic shutters. The embedded phase-detect AF system features 693 AF points spread across 93% of the frame, and operates at 60fps; Sony describes the AF speed as 25% faster than the A7r II.

The body becomes the first full-frame Sony mirrorless with dual SD slots (one exploiting UHS-II speed), and now features a new Z-series battery with 2.2x the life of W batteries, an AF joystick and touchscreen, along with dedicated drive mode and focus mode dials, an AF ON button, Ethernet port and a higher resolution quad-VGA (1280×960 pixel / 3686k dot) OLED electronic viewfinder with a 60 or 120fps refresh and again no blackout while shooting. Meanwhile there’s built-in 5-axis stabilisation with five stops of compensation that works with any lens you attach, along with 4k video using the full-frame or Super 35 frames, or 1080p at up to 120fps.

The Alpha A9 is unmistakably recognizable as a Sony mirrorless camera, sharing many design characteristics with the earlier A7 Mark II series bodies. But thankfully Sony has responded to criticisms and feedback over those models, enhancing a number of physical aspects from controls to storage and power to connectivity.

Measuring 127x96x63mm and weighing 673g including battery, it’s extremely close in size and weight to the A7r Mark II – indeed the same width and height, less than 50g heavier, and only a few millimeters deeper. The additional weight and depth is almost entirely down to the new battery and the grip which accommodates it, more about which later.

In your hands it unsurprisingly feels a lot like the A7r Mark II: compact but solid with enough of a grip and thumb rest to hold it securely and sufficient use of rubber surfaces to prevent slippage. Sony’s upgraded the build quality a little with greater use of magnesium alloy (now also in the grip), as well as employing six rather than four screws on the lens mount to better-handle large lenses. In terms of weather-proofing, Sony describes the A9 as being dust and moisture resistant, although wouldn’t be drawn over specifics or whether it was superior to the A7 Mark II series in this regard. Judging from the body and in particular the port doors, I’d say it’s essentially the same as the A7 Mark II bodies in terms of sealing; the flimsy port doors remain a potential weak spot with fiddly plastic flaps that clip into place, although at least the new memory card door seems fairly substantial.

Compared to other mirrorless bodies, I’d say Olympus still comes across as most confident against the elements with the OMD EM1 Mark II, and the company is happy to demonstrate it receiving significant splashes of dirt and water. But of course Sony isn’t pitching the A9 against the EM1 Mark II; with an asking price of over twice the Olympus and professional aspirations to boot, it sees the Canon EOS 1Dx Mark II and Nikon D5 as its peer group.

One look at the 1Dx Mark II or the D5 shows they’re physically completely different beasts. With their built-in portrait grips and giant batteries, both bodies are considerably larger, presenting an almost square front, and weigh over double the A9. For the record, the EOS 1Dx Mark II measures 158x168x83mm and weighs 1340g, while the D5 measures 160x159x92mm and weighs 1405g, making them both wider, deeper, much taller and considerably heavier.

So the Alpha A9 is smaller, lighter, more portable and certainly easier to squirrel-away in a bag or even a large coat pocket. But while the pro Canon and Nikon bodies are considerably heftier, they also feel more physically confident in your hands. I would have to leave each out in a shower to really see for sure, but I’m pretty sure the 1Dx Mark II and D5 are better sealed and more likely to survive a fall or hard knock too. Some photographers will also appreciate their larger grips and find their heft reassuring, especially when coupled with larger lenses. You can boost the A9’s heft by fitting the optional battery grip, but it remains a much smaller camera.

Sony’s Alpha A9 features one of the most modern and sophisticated approaches to continuous autofocus and burst shooting around, exploiting the benefits of an electronic shutter system more than any other company to date. Deploying the electronic shutter allows the A9 to shoot long bursts of 24 Megapixel images at up to 20fps in complete silence, without any vibrations, at shutter speeds up to 1/32000, and with no viewfinder blackout either. A handful of other recent cameras have also exploited electronic shutters for fast burst shooting, most notably the Olympus OMD EM1 Mark II, but the Alpha A9 is the first full-framer to really get behind it for action photography.
Electronic shutters have always been able to shoot in silence at high shutter speeds and without vibration, but what makes the implementation of the A9 unique is the sheer speed at which its stacked CMOS sensor can retrieve data. This is what allows it to minimize the traditional risks of skewing from a rolling-shutter while also delivering a live image while shooting with no blackout or lag between frames. Sony also reckons its banished previous limitations on dynamic range when shooting electronically, although I should note it does limit the maximum sensitivity to 25600 ISO. The speed of the sensor coupled with the front-side LSI also allows Sony to claim impressive buffer depths of 241 RAW files or 362 JPEG images when using UHS-II cards.
The ability to shoot silently at fast speeds with effective continuous autofocus allows you to capture shots at times that were literally out-of-bounds for traditional mechanical shuttered cameras. For example at some sporting events, it’s strictly forbidden to make any camera sound prior to contact with the ball, such as a golfer teeing-off. Traditionally, a photographer would have to wait for contact with the ball before they could start shooting, but now with the A9’s silent electronic shutter they can start shooting at the top of the back-swing.
While the A9 offers a mechanical shutter option (sensibly deployed with an electronic first-curtain only by the way), it’s mainly reserved for compatibility with flash and other artificial lights, or to access the camera’s maximum sensitivity of 204800 ISO. If you choose to shoot continuously with the shutter manually set to mechanical, you’re looking at the A7r Mark II’s fairly leisurely rate of 5fps with the usual viewfinder blackout and lag between frames. Set the shutter type to Auto and the A9 will select mechanical for single drive, but electronic for all the continuous burst modes, whether high, medium or low – and again all of these are delivered with no lag or blackout in the viewfinder. It’s clear Sony is sufficiently confident about the performance of the electronic shutter on the A9 that it’s effectively the default for burst shooting unless you go out of your way to circumvent it.
Whichever shutter you select on the A9, you’ll be using it with Sony’s best autofocus system to date, embedding a whopping 693 phase-detect AF points across 93% of the full sensor area. Compare that to the previous A7r Mark II which embedded 399 phase-detect AF points across 45% of its sensor area and it’s clear how far Sony’s progressed. Now the A9 can deploy the confidence and speed of phase-detect autofocus across almost the entire sensor, giving it the kind of frame coverage enjoyed by the A6300 and A6500, but with a much larger full-frame sensor area and the added benefits of zero blackout and 20fps bursts.

The A9’s vast array of AF points sounds overwhelming compared to the competition with Nikon’s D5 employing 153 AF points and Canon’s EOS 1Dx Mark II offering a relatively modest 61. But as always it’s important to understand not all AF points are created equal: a large number of the AF points on the Canon and Nikon are cross-type or even dual cross-type sensors which are sensitive to patterns in multiple orientations. In comparison, Sony has once again stuck with the simplest type of AF point, sensitive to a single axis only; interestingly Olympus is the only current mirrorless manufacturer to deploy cross-type sensors on an embedded array.

There’s no winner in this particular regard as there’s pros and cons to both approaches, but an advantage definitely enjoyed by the A9 is autofocus coverage. When shooting through their optical viewfinders, DSLRs employ separate phase-detect AF modules which concentrate their AF points into lozenge or diamond shapes, which on pro bodies occupy a roughly APSC area of the frame, leaving a thick border around it where the camera won’t autofocus. In contrast, the A9’s phase-detect coverage occupies 93% of the frame, allowing it to autofocus quickly and confidently track subjects even as they approach the extreme edges or corners of the frame; there’s no need to AF lock and recompose as you would with a DSLR. And while Canon’s Dual Pixel CMOS AF allows the 1Dx Mark II to autofocus in Live View across a similar area of the frame to the A9, it doesn’t do so as quickly, nor does it support the fastest burst speeds either.

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