Sony’s new a7 IV is the continuation of its core line of full-frame mirrorless cameras. It includes a series of upgrades but it’s also seen a price increase. Given how good the Sony a7 III was, we wanted to answer two questions: Which camera is the better buy, and is there any sense in upgrading?
In this article we’re going to take a closer look at these two full-frame cameras to see how they differ and try to help you work our which is the better choice for you.
On paper, the biggest difference between the two cameras is simply the sensor resolution, with the a7 IV making the jump to 33MP, rather than using the familiar 24MP chip used by the a7 III and several of its rivals.
For once this is perhaps the least significant difference: the new chip will certainly deliver a little more resolution and scope for cropping, but it’s the shift from the Bionz X-branded processor to one dubbed Bionz XR that leads to most of the meaningful differences, whether you’re a photographer or video shooter.
Both cameras can shoot at up to 10 frame per second, with the a7 IV only able to shoot destructively lossy Raws taken from 12-bit readout. The a7 III also lets you shoot vast, uncompressed Raw files at its fastest rate. However, when you don’t need so much speed, the a7 IV offers a lossless compression option for its Raw files, avoiding any risk of the odd artefacts that can become visible at high-contrast edges with heavy processing in Sony’s lossy Raw format, but without the huge files that uncompressed gives.
One of the biggest ways the two cameras differ is in terms of autofocus. The a7 III has a much older version of Sony’s AF system. It can find and automatically track eyes in the scene using a separate mode that overrides all other AF settings, but for other types of subjects it relies on Sony’s older, much less sophisticated tracking system, which wasn’t great at staying on the specified target.
Since then, Sony has developed a new subject tracking system that combines pattern recognition, subject color and brightness, face/eye detection, and distance information to provide much more dependable tracking. The a7 IV uses the latest version of this system, and its pattern recognition has been trained using machine learning to recognize a variety of subject types. So, whereas the a7 III might get distracted if your original subject looks away and there’s another pair of eyes for it to focus on, the a7 IV knows to look for a face or head where it last saw your subject’s eyes, maintaining focus on the person you asked it to prioritize.
In addition to people, the a7 IV knows how to recognize birds and animals. The upshot is a camera you can trust to focus on the subject you ask it to, in a way that’s not true of the Mark III.
User interfaces: menus
Both cameras have long and complicated menus, as you’d expect from models that offer so many modes and try to achieve so much for so many people. But we find the revised menus in the a7 IV much easier to navigate.
The a7 III’s menus features a series of horizontally arranged tabs, each with numerous sub-sections. These sub-sections have section headings but you need to scroll to the relevant page to see those section headings. The a7 IV’s tabs are vertically arranged, with the first seven sub-sections named on the screen as you enter each tab. This makes it much quicker to find, say, the ‘Movie setting’ sub-section, without having to memorize it as sub-section 9.
User interfaces: touchscreens and customization
The a7 IV also makes much better use of its touchscreen, letting you tap to navigate menus and the Fn menu to access them. The a7 III doesn’t let you do this, and reserves the touchscreen for setting the AF point and little else.
Both cameras let you customize their Fn menus, to put the 12 functions you want fast access to close-to-hand, but the a7 IV lets you create a separate stills and video Fn menu, so that you can access Picture Profiles (including Log modes) and focus peaking in video mode without these options crowding-out features such as Dynamic Range Optimization you might want for stills shooting.
The a7 IV lets you specify which settings (from white balance to shutter speed) are and aren’t carried over from stills to video shooting, letting you set it up for quick mode changes.
The a7 III has pretty decent ergonomics, offering front and rear control dials on the top of the camera, as well as a dedicated exposure comp dial and a little thumb dial on the back face of the body. It also has an AF joystick, absent from earlier models in the series.
However, the a7 IV gains all the little tweaks and improvements Sony has made to its design since then. The most obvious is that the dial on the top right shoulder of the camera can be re-purposed, rather than solely controlling exposure compensation, but there are a host of other changes, too. The AF-On button is larger and better placed, the rear joystick is also larger and flatter, making it easier to make precision movements. The a7 IV’s grip is also tweaked a little, providing a more comfortable hold on the camera. These are all small details, but they add up.
Video is another area in which the a7 IV stands head-and-shoulders above the older camera. The a7 III was one of the first full-frame cameras to shoot 4K video and gained a lot of features from the video-focused a7S II, but the market has moved on in the years since, and modern cameras are capable of more than this.
The a7 III could shoot 4K/24 from the full 6,000-pixel width of its sensor or 4K/30 from a 1.2x cropped region, both in 8-bit precision. The a7 IV can shoot 4K at up to 30p from the full 7,000-pixel width of its sensor and 4K/60 from an APS-C cropped region, and offers 10-bit capture for all its modes. Greater bit-depth delivers log footage that can tolerate more dramatic color grading before it begins to posterize, and also makes it possible to shoot Hybrid Log Gamma footage that can exploit the capabilities of HDR displays.
In addition to this, the a7 IV offers a Focus Map feature that lets you quickly preview the focus position and depth-of-field and, as discussed earlier, better separation of stills and video settings to allow jumping back and forth between modes. The a7 IV also has a mode that can crop and resize its video to cancel-out the zoom-like effect of focus breathing, with select Sony lenses.
All the comments we made about autofocus for stills are even more significant for video. The a7 III’s habit of drifting off to focus at a different distance is much more of a problem in video, where you clip is ruined as you try to coax it back to your intended subject, made worse by the reliance on much older, rather clumsy ‘center lock-on’ AF system.
The a7 IV’s much improved distance awareness and subject recognition (including eye/face) system is also available for video shooting, and the user interface for using it is much more consistent across the two modes, making the a7 IV one of the few cameras we’d confidently use in autofocus mode with moving subjects. Initiating AF a case of just tapping the screen on the a7 IV, whereas you need to engage a separate ‘Center Lock-On AF’ mode on the a7 III. You have control over whether the camera focuses fast (to maintain focus on one subject) or slowly (if you want the camera to gently pull focus from one subject to another), but that’s about all you need to adjust to use it.
The a7 IV is built around a 3.68M-dot OLED viewfinder, compared with the 2.36M-dot panel in the a7 III. That’s a shift from 1024 x 768 resolution up to 1280 x 960, so results in a 25% increase in linear resolution in each direction. Both cameras appear to use the same optics in front of those viewfinder panels, though, so the size of both finders (0.78x magnification) and the distance from which you can view them is identical.
Neither camera uses its full viewfinder resolution, by default. Both have ‘High Quality’ modes, that give a higher-resolution preview, but the resolution drops back to standard levels while autofocusing. The up-side is that the a7 IV’s ‘standard’ resolution appears to be more akin to the a7 III’s ‘High Quality’ setting, but without any change in detail levels or moiré when you hit AF. The a7 IV also offers a faster refresh rate mode in its standard resolution, which the a7 III doesn’t.
In terms of rear screens, the a7 IV again gets an upgrade, both in terms of the panel used and the way it’s able to move. The a7 III uses a 4:3 aspect ratio screen with 0.92M dots (640 x 480), whereas the a7 IV gets a wider, 3:2-shaped screen with 1.04M dots (720 x 480). The actual increase in resolution isn’t huge but the wider screen on the Mark IV is a better match for the shape of images the camera takes, meaning all of the panel is used for live view and playback, rather than having a settings bar along the bottom.
The a7 IV’s screen is also fully articulated, hinging out from the left-hand edge. This is convenient for video and waist-level shooting, and means you can rotate the screen in to face the camera to protect it from scratches. The a7 III’s screen tilts up and down but can’t be turned to face the user for vlogging or selfies.
The final big distinction between the a7 III and IV is the way they use Bluetooth. The a7 III could use a Bluetooth connection to grab location information from a paired smartphone, but its Wi-Fi system for transferring images was completely separate (you can tap a phone against the NFT aerial on the side of the camera to quickly initiate a Wi-Fi connection).
The a7 IV takes a different approach: it uses the Bluetooth LE standard to maintain a constant connection to a smartphone, so that either the camera or phone can initiate a Wi-Fi connection when you want to transfer images: an approach used, with varying degrees of reliability, by most other camera makers. Or, at least, that’s the theory. As yet we haven’t seen a version of Sony’s ‘Imaging Edge’ app that supports this feature. In principle the a7 IV should make it simpler and faster to transfer images.
Unlike most other brands, neither camera lets you re-process Raw files to produce an optimized JPEG before transfer, however.
The older models
While we’re primarily looking at the a7 III and IV, there are also older Sony models still on the market, with a7 II and high-res a7R II and a7R III bodies all available at competitive prices, because of their age. While the a7 IV sits at its newly-elevated list price, there’s an obvious appeal to older, originally higher-end models.
We’d generally caution against the Mark II models at this point: their UI and handling are significantly behind the performance of the newer models and their use of the smaller NP-fw50 batteries makes for a disappointing experience compared with modern FF cameras. The a7R III, then, is the only other model we think is worth considering. Its 42MP sensor gives a resolution benefit over the a7 IV, and it has the ergonomic improvements and larger battery of the basic a7 III, but again it can’t compete with the power and simplicity of the a7 IV’s autofocus system or the new camera’s video capabilities.
If you’re a landscape photographer that will appreciate the extra detail and probably isn’t dependent on subject-tracking AF, we think the a7R III is still a better choice than the a7 IV, but for most other users the AF, video and UI improvements would push us towards the a7 IV.
Ultimately, then, it all comes down to money. The a7 IV is a better camera than the a7 III in just about every respect. Not just its performance but also in terms of everyday usability. If you’re in the market for a new E-mount camera and you plan to keep it for a couple of years, we believe the additional cost, spread out across those years, is worth it for a camera that’s just that bit nicer to work with, in addition to the specific feature upgrades it gets.
The a7 IV is a better camera than the a7 III in just about every respect, not just its performance but also in terms of everyday usability.
But that’s not the same question as whether worth the money to upgrade, if you already have an a7 III. Again, the a7 IV certainly a better camera, and maybe you deserve something nicer, if you’ve been using the III for the past three years. But the III remains very capable. You’ll get the most out of upgrading if you shoot fast-moving (especially human) subjects: no matter how good you’ve got at using the a7 III, the a7 IV should perform better and make the task easier. Likewise if you’ve found yourself shooting a lot of video, the a7 IV offers clear benefits in that regard. But if you’re not pushing the camera in either regard, it might be that an extra lens could benefit your photography more than upgrading to the newest model.