Sony A7 vs A7 II vs A7 III: How do they compare?

When it was first introduced back in 2013, Sony’s original A7 was a big game-changer – squeezing a full frame sensor into an interchangeable lens camera that was smaller than a typical DSLR of the time, especially the sort of DSLR wielded by professionals.

Also new and unusual at the point it was released was that this new series of Sony cameras adopted the smaller Sony E-mount that was first used for the brand’s now discontinued ‘NEX’ compact system camera line up. Offering both high quality plus the convenience of portability and usability, it’s not so surprising that the A7 and its successive Mark II and Mark III siblings have increasingly found favor with photo enthusiasts and professionals alike.

All three built-to-last models feature full frame sensors – the original selling point of the series – with a respectable resolution of 24 effective megapixels apiece and images presented in 3:2 image aspect ratio. That’s something that has remained unchanged since the original launch of the A7. With this initial model and its successors Sony promised not only high resolution but also high sensitivity and extreme dynamic range, with low noise yet maximum detail into the bargain. Even in the A7, the sensor is married to the latest generation Bionz X processor, the combination helping to deliver realistic colours and swift burst capture.

The larger than average chip not only benefits stills capture – enabling images to be blown up large without noticeable loss in detail – but video also. On top of this, a 24.3 MP effective resolution is still very respectable/workable some five or six year down the line from the A7’s announcement, and pretty much what we’d still expect from a camera of its class and price. In terms of light sensitivity offered, the range is the equivalent of ISO200-25600 for up to Full HD video and ISO100-25600 for stills, expandable to ISO50 if desired.

The A7 II meanwhile was notable on launch for the claim of it being the world’s first full frame mirror-less camera with five-axis image stabilisation, the equivalent of a 4.5 step faster shutter speed. Again its full frame Exmor CMOS sensor was married to a Bionz X processor and effective resolution this time around was the same 24.3 megapixels. Core ISO sensitivity for this model is a respectable ISO50 to ISO25600, without the need for expansion.

By contrast the A7 III looks to be the best prospect in terms of low light performance, with its maximum expanded setting the equivalent of ISO204800, up from a relatively conservative maximum of ISO51200 for its native settings, before expansion. On this model Sony also claimed its (at the time) newly developed back-illuminated sensor when combined with Bionz X processor achieves a data-readout speed two times quicker than its predecessor and a data processing capability that is 1.8x higher. And who are we to argue with those benefits?

Plus, while the A7 and A7 II are both utilising the E-mount and offering compatibility with E-mount lenses, as regards the newer A7 Mark III, Sony is claiming improved mount rigidity over its predecessors. It notes that the number of screws securing the lens mount has been increased to six to ensure durability when using heavy optics – a distinct advantage given the appeal of this camera series to pros.

Longer in the tooth than its two successors here, the original A7 offers Full HD video at up to 60 fps – cutting edge at the time – or regular 24 fps clips, both recorded in Sony’s long favoured AVCHD format, with the alternative option of MPEG4 format if shooting at a lesser 1280x720 pixels at 30fps. The fact that we have an electronic viewfinder as well as rear plate LCD is also a bonus for when shooting video – we don’t have to otherwise switch to a dedicated Live View mode as one would with a DSLR with optical finder.

A jump from mark one to Mark II of the A7 saw the introduction of five-axis image stabilisation – a further boon for those shooting video; even if video resolution was still a maximum Full HD 1920x1080 pixels. Sony also added the option of recording in the pro quality high bit-rate XAVC S format on this model (alongside AVCHD and MPEG4 recording, naturally), while it further offers picture profiles, time code option and ‘clean’ HDMI output. The tilting LCD screen on the A7 series is obviously also a useful tool when shooting video – allowing for more high or low angle camerawork.

Both Sony’s first and second generation A7’s come at us with a belt-and-braces ‘hybrid’ auto focus system – much the rage at that point and indeed a feature still currently being developed further. The cameras feature 99 phase detection AF points and 25 phase detection AF points to ensure a best of both worlds response and, moreover, accuracy. On the original A7, a flexible spot AF area setting allowed for the biasing of a small, medium or large AF area, in order to match the size of the subject and ensure the camera stayed focused on what exactly we wanted it to stay focused on.

While the core AF spec may be very similar on the two initial A7 models, there’s a difference in the speed of response between the A7 and A7 Mark II, naturally. As regards the A7 II, its manufacturer claims AF response is 30% faster than its forebear. Once AF is locked on, it is also able to track moving subjects and theoretically keep them pin sharp, as one would expect of a camera in its class.

The pitch with Sony’s A7 III is that it utilises the same AF advancements as in its maker’s A9 model, enabling it to accurately capture unpredictable moving subjects, such as dancers and wildlife. There are 693 phase detection points (equally responsive when using an A-mount lens via adapter, as when utilising a dedicated E-mount optic), covering approximately 93% of the image areas, plus 425 densely packed contrast detection AF points to improve accuracy further.

Accuracy is delivered for low light shots down to minus 3EV. There is also eye detection tracking available when shooting stills in Eye AF mode, used in conjunction with AF-C (auto focus continuous) mode. Subject focus can also be controlled using the camera’s rear touch screen. In short, the camera provides a very versatile AF system for photographers, and one that seems a significant jump on from the previous A7 and A7 II models.

Indeed, the newer A7 Mark III can deliver a very respectable 10fps with auto focus/ auto exposure tracking, or a commendable 8fps if in live view mode. For when you don’t want to distract the subject there is also a silent shooting option; again this is up to 10fps with AF/AE tracking at maximum resolution. The conclusion would seem to be that if it’s plenty if poke you need for action and sports photography, then the Mark III has got to be your top choice of the three cameras.

Sony was trying to make a statement when it released the original A7 – namely that we could have a ‘pro’ grade camera that gave results akin to a full frame DSLR at a fraction of the bulk and weight of the equivalent model. Thus the A7 arrived with claims that it was 25% less bulky than comparative DSLR, while being much lighter too. Part of this was down to the magnesium alloy construction, delivering a body weight of 474g with battery and card inserted. This is not only half the weight of many DSLRs, but also lighter (if only by just over 100g) than the A7 II and A7 III models that followed it.

Unsurprisingly, given the class of camera and price tag, the A7 II again features a magnesium alloy build that manages to be both rigid yet relatively lightweight with it. The shape and height of the camera grip was also refined on this model, as were the operation of the shutter release button and dials – with the former being shifted forward to allow for more intuitive shooting and, in theory, less camera shake.

Sony suggests that the A7 III likewise offers a highly durable build, with resistance to wet or dusty conditions (with all major buttons and dials being sealed to minimise any possibility of entry). Again the top and front plates manufactured from tough magnesium alloy over an internal frame for added rigidity. Interestingly, it’s both slightly broader and heavier than the two cameras in the A7 series that came before it.

A bugbear of compact system cameras is that, typically, battery performance falls far short of their DSLR price equivalents. That was certainly the case when the initial A7 was introduced. It manages just 340 shots from a full charge of its lithium ion battery. While, to be fair, it’s not terrible when compared with the performance of other mirrorless models of the time, it certainly seems a little modest some five years on.

The A7 III is a lot better when it comes to battery performance than the first two iterations of the camera. So it suggests that if you can afford or justify the very latest version – which has not just a better power performance, but the latest must-haves like 4K video as well – then that’s probably your best bet.Again, as we can see from the above, the A7 III is marginally better when it comes to battery performance than the A7R II (according to CIPA standards), despite the use of the same battery. The difference between the two is unlikely to be significant in real-world use, however.

The runt of the litter when it comes to battery life is the A7S II, which manages only 370 shots when using its LCD screen, thanks to its non-Z-series battery. While this is certainly less impressive than the others, when it comes to the pro camera stakes, it's comparable with most compact system cameras from rival manufacturers; around 300-400 shots on a full charge is pretty much the industry standard, though this is improving with successive generations of camera.

You’re going to be basing your decision on which three of these Sony cameras that you choose largely down to your budget, we’d presume, with, typically, first or second generation models being cheaper than the very latest piece of kit that replaces them. That said, shop around for a good deal on the newest model if you can, as the Mark III does have all the bells and whistles that brings the series up to date and keeps it competitive when ranged against modern rivals.

If you don’t need 4K-video or if it’s stills in the main you’ll be shooting, then, arguably, there’s not a massive overall difference between the A7 and A7 II. That said; a rough rule of thumb is always to go with the newest model you can afford. As each generation of the series has been well received by us critics and wider photography community to boot, whichever you choose when it comes to Sony’s A7 series, there will be little room for disappointment.

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Gavin has over 30 years’ experience of writing about photography and television. He is currently the editor of British Photographic Industry News, and previously served as editor of Which Digital Camera and deputy editor of Total Digital Photography.

He has also written for a wide range of publications including T3, BBC Focus, Empire, NME, Radio Times, MacWorld, Computer Active, What Digital Camera and the Rough Guide books.

With his wealth of knowledge, Gavin is well placed to recognize great camera deals and recommend the best products in Digital Camera World’s buying guides. He also writes on a number of specialist subjects including binoculars and monoculars, spotting scopes, microscopes, trail cameras, action cameras, body cameras, filters and cameras straps.

Sony A7 vs A7 II vs A7 III: How do they compare?

Sony A7 vs A7 II vs A7 III: Sensor and processor

Sony A7 vs A7 II vs A7 III: Lens mount and compatibility

Sony A7 vs A7 II vs A7 III: Video

Sony A7 vs A7 II vs A7 III: AF system

Sony A7 vs A7 II vs A7 III: burst shooting (fps)

Sony A7 III vs A7R III vs A7S II: Viewfinder and LCD

Sony A7 III vs A7R III vs A7S II: Build and design

Sony A7 III vs A7R III vs A7S II: Battery life

Verdict

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