The Sony a7 IV is the company’s latest mid-range full-frame mirrorless camera, whereas the a7R III is a four year-old high-end, high-res model, so at first glance, they’re not the most obvious cameras to compare.
However, Sony’s habit of keeping older models in its lineup means they’re both still available. And, because the a7 IV is new, and still commanding its full MSRP, whereas the a7R III has been marked-down to sit below the fourth ‘R’ model, it seems like they’ll be comparable in price, at least at the moment.
A refresh, in the form of the a7R IIIA (ILCE-7RM3A), gains a higher-resolution rear display, suggesting Sony plans to keep it around for a while longer, so we think it still makes sense for us to try to address which of the two cameras is better.
Given that most modern cameras are very good, this article won’t simply declare one camera to be better than the other. Instead we’ll try to point out the relative strengths and weaknesses, so that you can work out which will be better for you and your photography.
Resolution and image quality
The a7R III was Sony’s highest-resolution camera when it was launched in October 2017, whereas the a7 IV is intended to be a more mainstream, do-everything model. As a result, the 42MP a7R III offers a clear benefit in terms of detail capture over the 33MP a7 IV. Looking at our studio scene, the ‘R’ can resolve finer detail than the newer camera can.
When mounted on a tripod the a7R III can also shoot bursts of four images, with the sensor moved by one pixel between each shot. These four files can then be combined on your computer to give an image with full color information at each pixel. The combination of multiple shots and the elimination of the need to demosaic gives improved detail, noise and dynamic range performance. This Pixel Shift Multi Shot mode only really works for static subjects, though.
But beyond this, there’s not much to choose between the two in terms of image quality. In terms of dynamic range both are very similar. The a7 IV switches to its higher gain step at ISO 400, rather than 640, but this is unlikely to make a big impact on most ways of shooting.
The other difference is that the a7R III can only shoot lossy compressed Raw (which can show image artifacts if you try to exploit the camera’s full dynamic range) or vast uncompressed Raws (82 MB per file). The a7 IV also offers a lossless compression option, meaning you can preserve the maximum possible file flexibility but in smaller files.
The Sony a7R III will automatically track eyes and faces and switch to generic subject tracking at the same point, if your subject turns away. The a7 IV though takes this concept much further, using more robust algorithms and is able to recognize humans, animals or birds.
The a7 IV uses a newer generation of AF system, with much more effective ‘generic’ subject tracking (following subjects that aren’t of a type that it’s been trained to recognize, as they move within the scene). In practice this means it’s more dependable and less prone to drifting off the subject you’d selected. The a7 IV is also rated as being able to focus in light one stop lower than the a7R III.
The a7 IV’s video autofocus is significantly more capable and reliable than that of the a7R III, since its system is built on a similar system to the one used in stills, rather than an older, more simplistic subject tracking system.
User interface and menus
One of the biggest differences between the two cameras is the layout of their respective menus. The a7R III uses Sony’s older menu with a series of tabs arranged horizontally across the top of the menu. This means you need to flip between the menu’s x sub-sections to find the one you’re looking for, which means memorizing roughly where each option lives.
By contrast, the a7 IV’s menu uses vertically arranged tabs, with the section headings for seven sub-sections visible immediately. This makes it faster to find the settings you’re looking for, and relies less on your memory. The menus in the a7 IV are also touch-sensitive, again making it easy to tap between tabs, which you can’t do on the a7R III.
The a7 IV gains the latest iteration of Sony’s ergonomics, which represent a significant improvement over the a7R III’s. The a7 IV’s hand grip is a little deeper, making it more comfortable when using heavier lenses, it also has a more prominent AF-On button and a larger, flatter AF joystick which is easier to make subtle movements with.
The a7 IV also gains a fair amount of additional customization, letting you customize the (now toggle locking) exposure comp dial on the right-hand shoulder of the camera. The a7 IV also lets you choose which settings carry over from stills to video and which don’t, so you needn’t have your stills-mode exposure settings or color modes spill over into your video shooting
It’s not just on the video side that the a7 IV gains 10-bit capability over the a7R III. The newer camera also lets you shoot 10-bit HEIF stills.
For a conventional workflow, this might not seem especially useful, given that 8-bit JPEGs look absolutely fine on most monitors and that Raw files will offer much more post-processing freedom than a HEIF will. The important point hidden in that statement is ‘on most monitors.’ 10-bit HEIF provides a next-generation JPEG alternative for capturing images for display on high dynamic range TVs and monitors.
Sony tends to use similar body designs across its camera ranges, so there aren’t especially big differences in moving up (and back) to the older ‘R’ model. The a7R III has a flash sync port, which the a7 IV lacks, but this is the only noticeable benefit (and one that’s easy overcome with a hot-shot to X-sync adapter, if you need to trigger external strobes with a wired connection).
The a7 IV instead gains a full-sized HDMI socket, which is much more robust than the micro HDMI connection on the a7R III.
The a7R III has one UHS-II SD card slot and one based around the slower UHS-I interface. The a7 IV has two UHS-II type slots, the upper of which has a CFexpress Type A slot set within it. This means the a7 IV can more readily use fast SD cards, and gives the option to use the slightly faster CFe format if you prefer. The a7 IV’s USB also uses the faster 3.2 Gen 2 (up to 10Gb/s), rather than Gen 1 (5Gb/s) on the a7R III.
Thankfully the a7R III is new enough to use the larger NP-FZ100 batteries and to offer a USB C connector, over which it can be charged. As a result, there’s no huge difference in battery life between the two cameras. Sony lists the a7 IV as using slightly more power, whether in stills or video mode or using the viewfinder or rear screen but the difference is relatively minor. The a7R III rated as 640 / 530 shots per charge, using the rear LCD and viewfinder, respectively, while the a7 IV gets a rating of 580 / 520 shots per charge.
Screens and viewfinders
Both cameras utilize 3.69M dot OLED finders with optics that give a 0.78x magnification, which suggests there’s a lot of overlap in hardware. Both cameras offer high res or high speed mode, which can’t be used in conjunction. In both instances there’s a resolution drop when you’re focusing, if you select high resolution mode.
The newer a7R III ‘a’ variant gained a higher-resolution rear LCD over the original a7R III. It’s a 2.46M dot panel which is likely to mean 960 x 640 pixels with a red, a green, a blue and a white dot for each pixel. The a7 IV’s panel is a 1.04M dot unit, giving a lower 720 x 480 display (probably with some white dots replacing some of the green ones to give a similar brightness/efficiency benefit). It means a 33% linear resolution difference, which is appreciable but not as dramatic as the dot counts might make it sound.
Perhaps just as significant a difference is that the a7R III has a screen that tilts up and down, whereas the a7 IV has a fully-articulated screen that hinges at the side. We tend to prefer the latter for video and portrait orientation shooting, and because it can be rotated to face in, protecting the screen.
If the full-sized HDMI port and fully-articulated rear display weren’t enough of a hint, let’s be clear that the a7 IV is a significantly more capable video camera than the a7R III.
The a7R III has a reasonable video spec, with a choice of rather soft, pixel-binned 4K from the full width of the sensor or more detailed footage if you apply an APS-C crop. There are plenty of options including S-Log3 capture but all the modes are 8-bit, which limits the amount of processing flexibility you get.
The a7 IV out-performs the R III in every regard. It can shoot 10-bit video including highly detailed, oversampled 4K footage from the full width of its sensor. This delivers much more gradable S-Log3 footage and allows capture for HDR TVs using the Hybrid Log Gamma standard. The a7 IV also offers direct video streaming over USB, allowing its use for live streaming or as a webcam.
The a7 IV also gains a mode that crops and upscales footage shot with select Sony lenses, to cancel out their ‘focus breathing’ (a change in angle-of-view as you change the focus distance). There’s also a depth-of-field indicator overlay, that lets you assess what is and isn’t within focus, as you shoot. But most critically, the a7 IV uses an autofocus system that’s much more closely modeled on the system used in stills mode, making it easier to use and more dependably than the clumsy ‘Center Lock-On’ AF system used by the a7R III in video mode.
Having said there wouldn’t be a simple conclusion to this comparison, a closer look shows the a7 IV stands out to a greater degree than we’d usually expect, when compared to a relatively recent, higher-end camera.
There haven’t been significant advances in image quality since the a7R III was launched and its 42MP sensor captures more detail than the a7 IV’s 33MP chip, even without considering its (rather clumsy, cumbersome) multi-shot high res mode. Its JPEG engine is recent enough to give an attractive color response and in terms of dynamic range and high ISO performance, it’s at least a match for the newer camera. In simple stills IQ terms, the a7R III is the stronger performer.
However, Sony’s constant iteration and improvements means that the a7 IV is simply a nicer camera to use. The autofocus, particularly when photographing people, is much more capable, the user interface is much improved, the buttons are that little bit nicer and better use is made of its touchscreen. In terms of video the a7 IV is a clear winner, and the constant Bluetooth connection means it plays with smartphones more readily.
If you’re shooting landscapes or studio photography that isn’t overly dependent on autofocus, the a7R III makes an excellent choice, especially if you can find one at a lower price than the a7 IV. But if you’re shooting moving subjects (and, in particular, people), the a7 IV will outdo the older camera. And in terms of usability and enjoyment, the experience of going back and using the a7R III makes it apparent how much progress the a7 IV has made.
This article comes from DP Review and can be read on the original site.