There are mirrorless cameras, and then there are mirrorless cameras. At the consumer end of the scale, they offer the best of both worlds – large image sensors capable of good image quality in a package that in many cases is all but pocket-sized.

The top end of the market is a different place. High-end, full-frame mirrorless cameras such as the Sony A9 throw caution to the wind, blending exotic sensor technology with supercomputer processing power to produce cameras that are nearly impossible to trip up, virtually silent in operation, and capable of incredible images that will withstand the most aggressive reproduction.

Sony A9 review: Specifications

You want specs? The A9 has a 24.2-megapixel, full-frame sensor, and is capable of shooting up to 20fps – impressively, this number includes mid-burst autofocus and auto-exposure adjustment, theoretically allowing you to track subjects not only as they move through space but also as they move through different light. It includes in-body image stabilisation that works on five axes (up/down, left/right and rotational movement), all housed in a weather-sealed, magnesium-alloy body designed to survive all but the most wilful abuse.

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Sony A9 review: Price and competition

You pay a pretty penny for it, mind. The A9 clocks in at the £3k mark without a lens, making it just about the most expensive mirrorless camera on the market, and placing it in direct competition with brand-new models such as the Nikon Z7 and the Canon EOS R – both up-to-the-second mirrorless DSLRs.

It’s also competing against traditional DSLRS – the Canon EOS 5D Mark IV and Nikon D850 are full-framers that will save you a ton of cash if you opt for them instead – albeit with a ton of compromises if you’re after a camera that can keep up with just about anything.

Sony A9 review: Features and design

The A9 is an unassuming little character – whereas the top-end cameras from Canon and Nikon are full-height monsters (the EOS-1D X Mark II and the D5 respectively), the A9 is barely bigger than most consumer cameras – indeed, at just 63mm deep it’s actually smaller than some.

It has a reassuring amount of heft, though. It weighs 588g with the battery installed, which again isn’t much for a pro camera but does make the A9 quite a dense bit of kit. It’s weather and dust sealed, and we’d have few hesitations about carrying on in poor weather.

It’s extraordinarily practical, too. The mode dial, drive mode, autofocus mode and exposure compensation all get their own physical controls, along with two variable-use dials, one under your index finger and another on the rear shoulder for your thumb. It might look a touch busy, but all those dials make the A9 an absolute dream to use.

You can adjust exposure very quickly whatever mode you’re in (it’s simulated live in the viewfinder which makes life even simpler), and because the main functions are represented by physical dials, it actually has the result of cleaning up the rear of the camera, which isn’t overly-festooned with controls. There’s a joystick, a thumbwheel and a few custom controls, and that’s it.

That leaves plenty of room for the screen; in this case a deluxe, 3in, 1.4-megapixel effort which can be angled up and down to suit your shooting angle. The screen doesn’t rotate, but that’s a minor quibble here, because it’s otherwise outstanding. Bright and sharp, it makes reviewing images and navigating Sony’s intuitive menu system easy. It’s a touchscreen to boot.

Still, the A9 is likely to be used with high-end lenses, which means the most comfortable way to shoot is via the electronic viewfinder. The EVF is another stellar example of its type – a 1.3cm, 3.7-megapixel display which, to all intents and purposes, is indistinguishable in its display of fine detail from an optical viewfinder - but with the added benefit of live exposure simulation.

It all adds up to a camera that’s an absolute beauty to use. It’s easy to find the features you want, particularly the most common variables you’ll reach for while shooting. It’s well balanced, lightweight and tough – so what’s underneath the resilient exterior?

In a nutshell: technology. Lots and lots of cutting-edge technology. The sensor might not be the absolute last word in resolution – it’s become common over the last year to see cameras with resolutions in the 50-megapixel ballpark, but the A9’s 24.2 is hardly impoverished, and will allow large-scale reproductions even without the huge native resolution of some of its competitors. The sensor itself is the first full-frame CMOS sensor with a stacked design, in which the pixelsites are bonded to image processing and DRAM layers, allowing the sensor to readout data extremely quickly.

That, in combination with the relatively low pixel count, allows the A9 to perform some very impressive, very fast tricks. The headliner is its maximum continuous raw framerate, which at 20fps is most of the way to cinematic framerates, and, amazingly, is faster than the Canon EOS-1D X Mark II’s 14fps (16fps in its electronic shutter mode) by 6fps. If you shoot sports there isn’t a faster-performing camera on the market.

But that stacked sensor doesn’t just shovel raw data fast. Because autofocus and exposure are performed on the sensor, the A9 is able to continuously calculate both up to 60 times per second, even while the camera is shooting. It’s not uncommon to find cameras with impressive burst modes, only to discover that the fastest frame rates are only available with AF and AE locked after the first shot. Not with the A9: if your subject moves or reflects more or less light in the middle of a burst, the A9 can follow it.

In use it’s incredibly impressive – with eye-detection turned on, the A9 stayed with a subject virtually flawlessly, and had no trouble tracking fast subjects. It’s no surprise to see the A9 cropping up in all kinds of professional scenarios – it makes challenging situations considerably easier to handle. A further benefit of the A9’s electronic shutter is that there’s no blackout between frames, which makes following subjects marginally easier. What’s more, the A9 offers phase-detect AF points across virtually the entire frame – 693 points in all. Photographers who like to blame their kit for out of focus images will need to start thinking of fresh excuses pronto.

Elsewhere, pro features abound. Wireless internet is commonly spotted, of course, but in-camera, background FTP uploading isn’t. A wired Gigabit Ethernet port is squirrelled away on the side as well, allowing you to upload via a lightning-quick wired connection, assuming your location has the ability. Elsewhere, the A9 is the only high-end mirrorless camera to offer two memory card slots – one is SD-only, the other can accommodate either SD or Memory Stick Duo numbers. Many pros consider single-slot cameras a distinct no-no, so the presence of in-camera redundancy will be appealing.

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Battery life is a slightly sticky wicket. The A9 will shoot about 480 frames on a single charge if you use the more demanding EVF, or just under 200 more if you frame up using the lower-power but more awkward LCD on the back. While we experienced slightly better performance than this, you will at the very least want a spare battery – if not two – if you’re expecting to use the A9 on a demanding shoot. Sony’s VG-C3EM battery grip, which houses two batteries at once, is available for £279 and may constitute a must-buy for some professionals.

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Sony A9 review: Photo quality

The A9’s technical qualities are for naught if it can’t take decent pictures, but, as you might expect, Sony’s sensational snapper doesn’t trip up here either. We tested with Sony’s FE 16-35mm F2.8 GM wide-angle lens, and were impressed by the overall sharpness, colour rendition and contrast, straight off the camera.

The results of our ISO tests were frankly ridiculous. With the image zoomed out, our test shots were indistinguishable from each other between the A9’s lowest ISO and – incredibly – ISO 12,800. Even with our tests zoomed all the way in, between ISO 100 and ISO 3200 there was no telling images apart.

In practical terms, that means photographers have five stops of flexibility, allowing them to shoot a huge range of shutter speeds or apertures in less-than-ideal light. Our test images remained broadly acceptable until ISO 25,600 and were – just – tolerable at ISO 102,400. The absolute maximum ISO of 204,800 is a party piece best avoided but make no mistake about it – the A9 is a low-light beast that anyone with a taste for low-light or astrophotography should have on the very shortest of shortlists.

The kind of images you can create make it a flexible beast as well. The Sony E-mount has gone from strength to strength over the last few years, and with lenses such as the FE 200-600mm f/5.6-6.4 G OSS, the FE 400mm f/2.8 OSS, the spectacular FE 600mm f/4 GM OSS and various other bits of high-end glass ranging from macro to superzoom, the A9 is compatible with a huge range of lenses. Sigma’s Art line is also available with an E-mount, further boosting the A9’s appeal to professional photographers.

Sony A9 review: Video quality

The A9 is a good, rather than an incredible, video camera. It records in 4K, of course, in 24, 25 and 30fps, and Full HD at up to 100fps (120fps in NTSC). Video quality – as suggested by our results testing the A9 in stills-only mode – is excellent, and niceties such as the audio-in jack provide videographers with a degree of flexibility. Unlike other high-end mirrorless cameras, though, there’s no LOG mode for recording flat footage for grading in the future, which restricts the A9’s video appeal somewhat.

Sony A9 review: Verdict

Every camera you buy will have some sort of ceiling on what you can do with it. On low-end cameras, this ceiling becomes apparent pretty early – limitations in terms of frame-rate, autofocus points and body controls all make themselves felt, and can cost you shots. With the Sony A9, the camera’s ceiling is somewhere in the stratosphere. Its autofocus grabs on fast and holds on with the tenacity of a dog wrestling a bone. Its continuous burst mode is breathtakingly fast and, although the camera perhaps looks sparingly appointed when it comes to physical controls, believe us when we say it isn’t – this is one of the easiest, fastest to use cameras we’ve ever come across. It takes great images, it’s compatible with a vast range of pro lenses, and its resistance to high ISOs makes it a good choice for when you absolutely have to turn in the goods irrespective of the light.

It’s imperfect, of course. It’s very, very expensive and battery life continues to be a challenge even for the best-designed mirrorless cameras. But for a camera with the horsepower to more or less vanish while you return sharp image after sharp image, even in poor light and with dynamic subjects, it’s hard to think of very many better options.

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