Sony is a leader in mirrorless cameras with its full-frame Alpha series, but as the series has expanded to four models, choosing the right one can be confusing. In the current lineup, the A9 II, A7 III, A7R IV, and A7S II are all capable models, but each has unique advantages that may make it better or worse in any given situation.

The most obvious difference in these cameras is the sensor resolution, which varies considerably from the A7R IV’s 61 megapixels down to the A7S II’s 12. The A9 II and A7 III take up the middle spots with 24 megapixels, but the A9 boasts higher performance — and a much higher price. With hands-on experience with nearly every full-frame Sony mirrorless model since the series launched in 2013, we’ve pinpointed the differences to help you figure out which is best for you.

Sony A9 II

If it’s speed and precision you need, it’s the Sony A9 II you want. The original A9 wowed at launch with its 20-frames-per-second burst speed. The second-generation camera adds more incremental steps than monumental changes, but it’s still Sony’s top-performing model. Sony’s flagship camera uses a full-frame Exmor RS backside-illuminated (BSI) CMOS sensor that’s stacked to proved that exceptional speed. It’s paired up with the latest Bionz X image processor for better performance across the board.

Its stacked sensor measures in at “only” 24 megapixels, but what it lacks in resolution, it makes up for in performance. It isn’t just fast, but can hold that 20 fps speed for over 200 exposures in compressed RAW format. Compared to the 14 fps of Canon’s flagship 1D-X Mark II and 12 FPS of Nikon’s D5, it’s nothing short of mesmerizing.

The sensor also has an extended ISO range of 50 to 204,800 and can fire its electronic shutter as fast as 1/32,000 of a second, a fast enough speed that rolling shutter distortion is much less of a concern than with other electronic shutters.

The A9 II’s autofocus system consists of 693 phase-detection AF points and 25 contrast-detection points. In total, the autofocus points cover more than 93 percent of the frame and focus calculations are made 60 times per second — more than enough for even the most demanding environments and subjects.

Complementing that speed and focus precision is the 3,686k-dot OLED electronic viewfinder that offers a no-blackout display when shooting bursts. With the electronic shutter, the A9 II makes viewfinder blackout a thing of the past, meaning the entire time you’re holding down the shutter and taking photos, you’re still seeing a live view of exactly what the sensor is seeing, even at 20 fps.

The A9 II is also weather-sealed, has dual SD card slots, and features both wired (Ethernet) and wireless (Wi-Fi, NFC, and Bluetooth) connectivity. And while it isn’t Sony’s best video camera, it still shoots 4K video at 30 fps.

Priced as it is, it’s not exactly a consumer-centered camera. Thankfully, many of the technologies from the A9 have trickled down into Sony’s other full-frame models. Or, if you really need that speed and can’t swallow the price, the first-generation Sony A9 is still around, too.

Sony A7 III

Sony might call the A7 III the basic model of its lineup, but it’s far from basic in our book. Its 24MP backside-illuminated sensor brings along improved low-light performance and increased dynamic range compared to the already very capable A7 II. It also strikes a good balance between file size and resolution. It won’t match the detail of the A7R VI, but for most situations it has more than enough resolution.

The A7 III boasts the same 693-point autofocus system found inside the flagship A9 II, and AF performance is equally quick and reliable. Battery life is doubled compared the previous generation, at 710 shots per charge, putting it well ahead of the mirrorless competition.

As with other third-generation A-series cameras from Sony, the A7 III now has a burst rate of 10 fps. In full continuous mode, it can shoot 177 JPEGs. This isn’t the professional sports camera that is the A9 II, but it is impressive for a “basic” model.

The A7 III also stands strong in its video capabilities. It shoots oversampled 4K from the full width of the sensor, so there’s no cropping and no pixel binning. You also get various high-end features, like S-Log flat color profiles that preserve dynamic range and offer more flexibility for color grading.

As the specs show, the A7 III is anything but basic. From a value standpoint, it is likely the best camera on this list and the one most people should buy, even if your budget is higher. The money saved here can be put toward a good lens.

Read our Sony A7 III review.

Sony A7R IV

The A9 II may be Sony’s top performer, but the A7R IV is the high-resolution champ. It uses a 61MP, backside-illuminated (BSI) CMOS sensor. That resolution makes the A7R IV the highest resolution full-frame camera — it turns out images that are more than 9,500 pixels wide. It also has one of the highest-resolution electronic viewfinders at 5.7 million dots.

If somehow that’s not enough resolution for you, the camera’s Pixel Shift Mode can produce a 240MP image. As of now, the final image must be processed on a computer using Sony’s software, so it’s not the most convenient option, but it’s still an impressive feat.

Despite that crazy high resolution, the A7R IV still manages a 10 fps burst mode, although RAW files go from 14-bit to 12-bit when shooting at full speed. To help manage the increased image output, Sony has taken a page from the A9 and added dual memory card slots, both compatible with fast UHS-II SD cards.

When it comes to autofocus, the A7R IV uses 567 phase-detection points and 425 contrast-detection points. Sony also boosted the autofocus algorithms to allow better tracking for moving subjects and Real-Time Eye AF.

When it comes to video, the A7R IV impresses again. It can shoot 4K either in full-frame mode, or from a cropped, Super35mm-sized region of the sensor. In Super 35 mode, which uses a 1.7X crop, it oversamples additional pixels for an extra-sharp 4K image. Like the A7 III, It also uses S-Log, a flat gamma profile that captures the maximum dynamic range and is suitable for color grading.

Processing all those pixels takes power, but the A7R IV still ekes out 670 shots on one battery, or 530 when using the electronic viewfinder.

The A7R IV won’t be for everyone. It is meant for photographers who are willing to put in the time to get things right. But if that’s you, the A7R IV promises the best possible image quality you can get, shy of top-of-the-line medium format systems. Like other Sony full-frame mirrorless cameras, the previous generation Sony A7R III is still available, offering a lower price point without quite so many megapixels.

Read our Sony A7R IV hands-on review.

Sony A7S II

The A7S II is the only model that hasn’t yet been updated into the third generation. It is the most narrowly-focused camera of the three A7 models, and the hardest to recommend. With just 12 megapixels, it falls quite a ways behind the resolution of most current mirrorless cameras, even lower-end consumer models.

That low resolution, however, means each individual pixel is much larger and therefore more sensitive to light. The A7S II’s ISO range can be expanded up to 409,600, so you can pretty much shoot under moonlight. It’s not the highest ISO rating out there (the Nikon D5 pushes into the millions) but it’s more usable than most.

But being as old as it is, the A7S II lacks the best autofocus of newer Sony cameras. The 169-point AF system relies completely on older, slower contrast-detection technology. It also can’t track moving subjects in continuous shooting mode, as the AF stays locked after the first frame. So even as the sensor is built for low light photography, you may get better results with something like the A7 III.

The A7S II’s other primary focus is video. It can record beautiful 4K footage from the full width of the sensor, although it doesn’t have enough resolution to shoot 4K from a Super 35 crop. It will, however, shoot 1080p in crop mode at up to 120 frames-per-second for slow motion. Naturally, it also uses Sony’s latest S-log profiles, providing the most flexibility in post-production.

Read our Sony A7S II review.

Previous generation models

While the focus of this story is on the latest cameras, we should note previous A-series cameras are still available for sale. What they lack in new features, they make up for in lower prices. The A7R II has the same high-resolution sensor as the Mark III model, while the A7S is a low-light champ just like its younger, second-generation sibling, and the first generation A9 boasts the same speed as the newest option.

The most attractive model is likely the A7 II. It won’t quite match the ISO performance or dynamic range of the A7 III, but it still uses a 24MP sensor capable of producing some brilliant images. For still photographers on a budget who want to move into full-frame, its low price makes it quite enticing.

So while we all love the latest and greatest tech, you can save a lot of money by buying a model from the prior generation, money that could go to lenses, flashes, or other accessories that may make a bigger difference in the quality of your images. If you don’t need the latest speed and features, the A7 II, A7R II, a7R III or A7S might be the right camera for you.

Sony A7 II review | Sony A7s review | Sony A7R III review | Sony A9 review

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