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Sony A7R IV vs. A7R III: An extra 20 megapixels isn’t the only difference

The Sony A7 series revolutionized mirrorless cameras as it was the first to use a full-frame sensor. The original A7R launched over six years ago and Sony has continued to improve on it, having released the fourth generation in 2019. The A7R IV comes 2 years after its predecessor, and while there are some striking differences, there are a number of similarities. Here’s how the Sony A7R IV and A7R III compare.

Sensor

The most significant difference in the Sony A7R IV is the sensor. Sony has never been lacking in this department, but it still decided to put a brand new sensor in the latest model. The A7R III’s 42-megapixel sensor is no slouch, but the A7R IV packs in nearly 20 more megapixels with its 61MP unit. That makes it the highest-resolution full-frame sensor available, and is another groundbreaking move from Sony.

That sensor even has more megapixels than several medium-format cameras, like the 50MP Hasselblad X1D II, although it comes up shy of the 100MP Fujifilm GFX 100. It’s no surprise that Sony is waxing lyrical about the camera’s ability to match medium-format quality.

Beyond resolution, both the A7R III and IV have 15 stops of dynamic range, according to Sony, and independent tests have essentially shown this to be true. Both cameras also have a wide ISO range that starts at a native 100 and tops out at 32,000 (both can be extended from 50 to 102,400.) If you don’t have a need for the extra megapixels, the A7R III will deliver image quality that is essentially the same as the IV.

Autofocus

Another area in which Sony has been a trendsetter is autofocus. It’s the only company to claim an autofocus speed of 0.02 seconds. Autofocus on the A7R III was already impressive, but the IV received some serious upgrades. It has a staggering 567 phase-detection points compared to the III’s 399. Both systems have 425 contrast-detection points.

More importantly than the number of points, Sony has made improvements to its focusing algorithm. While Real-Time Tracking and Real-Time Eye AF — Sony’s artificial intelligence-based focusing tech — made their way to the A7R III via a firmware update, these systems work even better in the A7R IV. The camera can differentiate subjects, from humans to animals, and performance is more reliable overall. Overall, it’s simply the best autofocus system we’ve tested.

Video

The video capabilities on both cameras are pretty similar, and while neither is one of the best video cameras, both shoot Ultra HD 4K (3,840 x 2,160), and the A7R IV can also output DCI 4K (4,096 x 2,160) over HDMI. You won’t find 4K/60 on either camera as each tops out at 30 frames per second.

The biggest difference between the two comes in how the cameras crop the sensor in Super 35 mode. This shooting mode uses a smaller area of the sensor, roughly equivalent to Super 35 film or an APS-C sensor, which bypasses the pixel binning required to turn the 42 or 61 megapixels into the 8.3 required for 4K and thus produces sharper results. However, where this mode used a 1.5X crop on the A7R III, it uses a tighter 1.6X or 1.8X crop on the A7R IV, depending on if you’re shooting 24 or 30 frames per second. This reduction in field of view can make it difficult to get a wide-angle shot.

But the A7R IV still has an edge: Real-Time Eye AF. While this autofocus mode is reserved for still photography in the A7R III, it is available in video mode on the IV.

Build

Both cameras are very similar when it comes to size and weight. The A7R III has dimensions of 5 x 3.8 x 2.9 inches and weighs 1.45 ounces. The A7R IV measures 5.07 x 3.8 x 3.05 inches and weighs slightly more at 1.46 pounds.

But larger and heavier isn’t a bad thing in this case. The difference in size is most notable in the A7R IV’s grip, which sticks out further for improved ergonomics. The A7R IV also comes with upgraded weather sealing and is built to hold up to professional wear and tear.

There are a handful of minor changes to the layout of the rear of the camera. The AF joystick is larger, as is the AF-ON button. The exposure compensation dial has a new lock button to keep your settings fixed in place, an option that was missing on the A7R III.

The biggest point to celebrate in the latest model is the change in shutter. The new shutter has been designed to reduce shutter shock, which is vital with such a high-resolution sensor. As the smallest vibrations can reduce image quality, having as soft a shutter as possible ensures you can get the most out of those 61 megapixels.

Minor differences between the Sony A7R IV and III

Some slight changes have been made to different parts of the camera, which are worth noting.

The A7R IV now has an OLED electronic viewfinder with a resolution of 5.7 million dots. That’s an increase over the 3.7 million dots in the A7R III. The extra resolution means a clearer, more detailed view both for framing your shot and reviewing it.

Both cameras have two SD-Card slots, but only on the A7R IV are they both UHS-II compatible for high-speed media. The A7R III has one UHS-II slot and one UHS-I slot.

Battery life has also been improved slightly, from 650 to 670 shots, although both cameras use the same NP-FZ100 battery.

Should you upgrade?

The Sony A7R IV is an excellent camera — and our pick for best camera of 2019 — but does it warrant spending $3,500? Unlike a lot of new models, there have certainly been some significant changes made to the A7R IV, and the new sensor is sure to turn some heads, but few people actually need 61 megapixels.

However, we know this industry isn’t always about needs, and can often be about what we want. If you decide to upgrade, it certainly isn’t a bad choice. Putting the sensor, AI tweaks, shutter, video, and build together, enough is going on with the Sony A7R IV to make it a more than justifiable purchase.

If you’re looking at your first A7R model, the III is now considerably cheaper than when it launched, selling for about $2,500. That’s a fantastic price for a camera that remains extremely competitive today with the best professional-grade cameras out there.

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