The A7R III came out in October 2017 and is still a very popular full frame camera today, thanks to its excellent image quality and fast performance.
Of course when it comes to technology, a four year gap is significant and the new products that arrived in 2021 have made some interesting progress. The A7 IV is one of the latest examples among Sony E-mount cameras.
In this article, we compare old and new to see exactly how much of a difference there is.
Note: the original A7R III has been discontinued and replaced by the A7R IIIA. The differences are minor, with the most noticeable thing to highlight being extra resolution of the LCD monitor (2.36M vs 1.44M dots) and the faster USB C port (5Ghz).
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1. Image quality
The A7 IV and A7R III incorporate a full frame (35mm format) sensor with a BSI design (back-illumination) and no low-pass filter.
The first difference concerns the megapixel count: the new A7 IV has 33MP, whereas the A7R III has 42.4MP.
The second difference is the ISO range, which is slightly wider on the mark 4 model:
|A7 IV||A7R III|
In addition to the larger ISO range, the A7 IV also gets the latest image processor (BionZ X) which is much faster than the previous generation found on the A7R III (BionZ X).
There are a few other things to highlight when it comes to image quality.
The A7 IV features the new picture profiles, called Creative Looks, which replace the older Creative Styles found on the A7R III. This means that the A7 IV also includes the latest improvement to colour rendering, seen first on the A7S III.
On the new camera you will also find the HEIF format (HDR 10-bit still image), in addition to JPG and RAW.
Another welcome addition is the possibility to shoot with Lossless Compressed RAW files on the new camera, in addition to Compressed and Uncompressed. On the R3 model, the Lossless option is not available.
2. Extra colour resolution
The A7 IV and A7R III have in-body image stabilisation, also known as 5-axis stabilisation, with a rating of 5.5 stops of compensation.
Unique to the A7R III however, is the possibility to use this technology for another purpose: increased colour resolution.
When the Pixel Shift Multi Shooting mode is enabled, the R model takes four images in a row and moves the sensor’s position by one pixel between each frame.
Then, when compositing the four images in post with the Sony Imaging Edge software, you obtain a photo that retains the same resolution of 42MP, but with more colour resolution because each point on the image was captured by at least one red, blue and green pixel.
Not only do small details become more defined, but this method also gets rid of any moiré that would be present in a single shot.
Keep in mind that this mode must be used with the camera fixed on a tripod, and will create artefacts if there are moving elements inside the frame.
The two cameras feature a hybrid autofocus system with phase and contrast detection, but there are a lot of differences to talk about, starting with the number of AF points.
- A7 IV: 759 phase, 425 contrast
- A7R III: 399 phase, 425 contrast
The phase detection points of the A7 IV cover an area of approximately 94% on the sensor, whereas the coverage is smaller on the A7R III (68%).
Then we have the software: the A7 IV features the latest algorithm with deep learning technology, which includes real-time tracking where the camera analyses the image on different levels (face, eyes, colour, depth and distance).
Furthermore, Eye AF works for humans, animals and birds on the new camera for stills and video.
The A7R III doesn’t have real-time tracking so it relies on the older Lock-On AF mode. Eye AF is available for humans and animals (not birds) but only works when taking photos.
In low light, the A7 IV has more sensitivity with a rating of -4 stops vs -3 stops on the A7R III (with a f/2 aperture).
Finally, the A7 IV has more advanced settings to control the autofocus for video, as well as the AF Assist option that allows you to change focus manually while working in C-AF mode.
4. Speed and buffer
Despite the difference in sensor resolution, the two cameras share the same continuous shooting speed of 10fps maximum. That speed works with C-AF and exposure tracking.
One thing to understand, according to the first reviews (DPreview, Camera Labs), is that the A7 IV can work at 10fps only when shooting JPGs or Lossy Compressed RAW. With other RAW settings (lossless compressed or uncompressed), the speed drops to 6fps. Furthermore, with Lossy RAW, you need the CFexpress card to achieve the maximum speed, otherwise it’s 8fps with SD UHS-II cards.
By comparison, the A7R III remains close to 10fps even with uncompressed RAW.
Where the A7 IV has an advantage is with the buffer memory, or how it captures images at full speed.
The new camera, thanks to its compatibility with CFexpress cards, can record more than 1,000 files (JPGs, or lossless compressed RAW).
The A7R III can do a much more modest 76 JPGs, 76 RAW (compressed) or 30 RAW (uncompressed).
5. Video capabilities
Here we find perhaps one of the major differences between these two cameras.
First of all, let’s talk resolution and frame rates. The A7 IV can record 4K up to 30p with no sensor crop and full pixel readout without pixel binning (in other words, at the best quality possible).
You can increase the frame rate to 50 and 60p, but for that you’ll have to accept a 1.5x crop on the sensor (aka Super35/APS-C mode). Full pixel readout and no binning still applies.
The A7R III can record 4K up to 30p only. You have the choice of working in full frame mode, or with the APS-C crop. In full frame mode, the camera does line-skipping, so detail rendering won’t be perfect and you can encounter some aliasing. For the best quality (oversampling), you need to use the crop mode.
Then we have bitrate, compression and colour depth, and here the A7 IV offers many more possibilities. In short, you can record internally and save more colour information, as well as work with a higher bitrate and better compression. In the table below, you’ll find the main features.
|A7 IV||A7R III|
|10bit 4:2:2||internal / HDMI||n.a|
|S-Log2 / 3||yes||yes|
Another important difference is that the A7 IV doesn’t have a recording limitation, so you can go beyond the usual 30 minute limit per clip (which is a growing trend in the digital camera industry). Sony says you should be able to do at least one hour in 4K 60p with 10-bit 4:2:2.
In Full HD, both cameras go up to 100fps (PAL) or 120fps (NTSC).
The A7 IV also gets extra settings, such as the Active stabilisation boost, post production stabilisation with the Catalyst software and Breathing compensation among other things.
6. EVF and LCD
The two cameras share the same viewfinder, with 3.69M dots, 0.78x of magnification, 23mm eyepoint and a maximum refresh rate of 100Hz / 120Hz.
The rear LCD presents a few differences however. First, the one on the A7 IV has a multi-angle mechanism and includes the 180˚ orientation. On the A7R III, the monitor tilts up and down only (max. 90˚, approx.).
Another difference is the resolution. The A7 IV screen has 1.04M dots, whereas the original A7R III had 1.44M dots. The replacement A7R IIIA has a much better monitor with 2.36M dots.
Either way, both LCDs are touch sensitive but the A7 IV gives you more options of use, including navigating the menu. On the R model, you can only move the AF point or double tap to activate focus magnification.
7. Design and controls
The A7 IV shares the same design as the A7S III, which is the latest update and displays a few differences in comparison to the previous generation (A7R III).
The dimensions are similar, but the A7 IV is a bit bigger in order to accommodate the heat dissipation structure, which helps the camera to record 4K video for a long time without overheating. They are both weather sealed.
- A7 IV: 131.3 mm x 96.4 mm x 79.8 mm, 658g
- A7R III: 126.9mm x 95.6mm x 73.7mm, 657g
The new camera has a larger front grip, and some buttons have a more pleasant tactile feedback. The video recording button is found on top of the A7 IV, and on the rear of the A7R III (near the viewfinder).
Another upgrade concerns the customisation possibilities: the exposure compensation dial can be customised on the A7 IV (and has a lock button), plus the camera has extra settings, for example to change parameters such as the aperture independently in stills and video mode.
Sony has also made it easier to go from stills to video mode on the new camera by adding a secondary dial under the main one on top, and this means you can now use the PSAM dial to change exposure method in movie mode too (on the A7R III you need to go inside the menu for that). The menu system changes accordingly when going from photo to video or S&Q mode.
Other things that are only available on the A7 IV are:
- digital audio via the multi-function shoe on top of the camera
- full sized HDMI port (vs Micro on the R model)
- latest menu design
- 10Gbps USB Type C port (vs 5Gbps on the R model)
What remain the same is the battery type (NP-FZ100) with a similar rating, as well as audio in & out connections. Both cameras can be charged or powered via USB.
8. Memory cards
Both cameras can work with two memory cards simultaneously.
On the A7 IV, both slots are compatible with UHS-II SD cards, and slot nb.1 can also use the faster (and more expensive) CFexpress Type A (not to be confused with Type B which is larger and won’t fit).
The A7R III has two slots for SD cards, and only slot nb.1 is UHS-II compatible.
9. More features
The A7 IV is a more recent product, and as you can expect, it has extra options you won’t find on older cameras such as the A7R III. These include, for example:
- Focus Map: you can visualise the depth of field with different colours (red is behind, blue is in front).
- Variable Shutter: it allows you to select the shutter speed with more precision than the default 1/3EV step, which is useful to eliminate flickering of select light sources such as LED
- Anti-dust Function: it keep the mechanical curtains down when the camera is powered off, covering the sensor.
- USB Streaming: the A7 IV can work as a common webcam without the need to install additional software on your computer, unlike the A7R III that needs the Sony Imaging Edge Webcam app.
The A7 IV has been launched with the retail price of $2500, £2400 or €2800.
The A7R III / A7R IIIA can be found for $2800, £2200 or 2300€
Note: prices are for the body only and as of October 2021. The original A7R III (without the “A”) can still be found in a few stores, but the price is the same as the A model, so you might as well buy the latter.
The A7 IV feels like a more complete package overall thanks to the autofocus and video improvements, as well as an updated body design and various extra features found in the refreshed menu system.
That said, the A7R III remains a competitive proposition, especially if we look at image quality, because its 42MP sensor is still one of the finest you can find. If you shoot RAW and like landscape or still life photography, I think the A7R III remains an interesting choice in 2021 and surprisingly, it seems to handle continuous shooting a bit better than the mark IV model.