Introduction The EOS R3 is Canon's highest-end mirrorless camera yet, but it arrives into a range of already capable cameras. The EOS R5 impressed us a great deal, proving itself a worthy successor to the classic EOS 5D DSLRs, so what does the R3 do that's different, and is it worth the extra money? The all-around capability of the R5 and the branding of the R3 mean it's not quite as clear-cut as the distinction that existed between the 1D and 5D models.
But it still essentially comes down to what you want to use the camera for. Let's take a closer look at the two cameras' respective strengths.
Sensors
We wouldn't usually start a comparison by talking about sensors, but the difference in chip technology between these two cameras is at the heart of most of the other differences between them.
The EOS R5 uses a front-side illuminated CMOS sensor. It performs very well, both in terms of image quality and speed. But using electronic shutter drops to 12-bit mode and still takes around 1/60th of a second to read out the whole sensor, which means no use of flash in e-shutter mode and a risk of moving subjects appearing distorted if they move too much during that 1/60th of a second.
The EOS R3 jumps two generations ahead: skipping conventional BSI fabrication and moving on to a Stacked CMOS that allows much faster readout. The R3's electronic shutter takes around 1/200th of a second to read: approximately 1/3rd as much time. This means flashes can sync at up to 1/180 sec in e-shutter mode and it's much less likely that you'll see any rolling shutter effect. It's only a fraction slower than most mechanical shutters, which typically take around 1/250 sec to traverse the sensor.
This speed difference plays a role in several of the cameras' features, but the most fundamental is that the R3's e-shutter mode can be used for almost all photography, whereas the R5's is more limited.
Shooting speed
The faster burst rate of the EOS R3 puts it more in line with Canon's 1D series of pro sports DSLRs
The difference in readout speed makes a fundamental difference to the circumstances in which you can use the electronic shutter that underpins both camera's fastest modes. So, while it may appear that the R5 can shoot at 20 fps to the R3's 30, in many circumstances it's not advisable to use e-shutter mode.
The difference is that the R3's super-fast readout means e-shutter can be used for shooting even fast-moving subjects at its full 30 frames per second, but the R5 would need to be switched to its 12 fps mechanical shutter mode.
It depends on your tolerance for rolling shutter distortion, of course, and there are scenarios in which capturing the perfect moment but with a slightly elongated subject is good enough. But this isn't likely to be the case for anybody being paid to capture sports photos, and hence the R3 will significantly outperform the R5 for shooting action.
Resolution
Just as with the 1D / 5D relationship, if you're looking for a high-res landscape or studio camera, it's the smaller camera that's a better bet.
The 45MP FSI CMOS chip in the EOS R5 delivers the goods in terms of resolution, and its dynamic range is solid, too. We say solid because, although it measures very much like Sony's a7R IV, there seems to be a little detail smearing noise reduction going on in the shadows of low ISO Raw files to help make the numbers look good.
We've not been able to see if anything similar is happening with the R3, but its 24MP sensor is not going to match the R5 in situations in which detail capture is critical.
Video spec
The EOS R5's higher resolution sensor gives it an edge in terms of video, too. It can shoot 8K footage at up to 30p, which the R3 simply hasn't got enough pixels to keep up with. However, 8K is overkill for a lot of applications; mainly providing scope for cropping or downsampling, to give more detail than native 4K capture can achieve.
And it is in this second regard that the R3 starts to close the gap a little. It can't quite match the detail levels of the R5's 4K-from-8K, but its 4K footage at 60 fps or slower is all taken from the full 6K width of its sensor (in DCI mode, anyway*). So you can get 1. 5x oversampled 4K footage at up to 60p, which the R5 can't do. The R3 also has connectors in its hot shoe that allow the attachment of an external XLR mic adapter.
Then, of course, there's the consideration of heat build-up. Both cameras have thermal limits in their more demanding video modes, but Canon says there's no particular restriction on 4K (from 6K) shooting at up to 30p, whereas the R5's oversampled 4K shooting duration is limited and gets cut into by any prior use of the camera. Overall, the R3, with its larger battery, is likely to be the more usable video tool.
*16:9, UHD 4K comes from a 5. 6K region, cropped in at the edges.
Viewfinder/screens
In terms of screens, both cameras have side-hinged fully-articulating rear touchscreens, well suited for video and tripod work but perhaps not ideal for portrait-orientation shooting. The R3 has the more detailed LCD panel, with 4. 15M dots giving a resolution of 1440 x 960 pixels, rather than the 1024 x 680 pixels that the R5's 2. 1M dot screen can deliver.
There's a difference in terms of the viewfinders, too, even though the specs don't necessarily give it away. Both have 5. 76M dot panels with 0. 76x magnification, the same 23mm eyepoint, and the same -4. 0 to +2. 0 diopter adjustment. Both can be run at 120Hz if you engage 'Smooth' refresh mode, but the R3's viewfinder also has an 'Optical Viewfinder Simulation' mode, which exploits the viewfinder panel's wide dynamic range to give a more realistic view of the world. Our initial impression is also that the R5 doesn't necessarily always utilize the full resolution of its panel.
AF performance
The EOS R3 has a more sophisticated autofocus system, partly because it's a newer camera, but mainly because action is such a core part of the audience it's targetting.
Both cameras have subject tracking that will try to recognize and prioritize people when asked to track human subjects. This taps into a system trained by machine learning that recognizes eyes, faces and heads, so that it will continue to track your subject even if they turn away from the camera (rather than refocusing to other faces in your scene, for instance).
Both cameras can also recognize and track a variety of birds and animals, if told to do so. The R3's AF system also has a mode that's been trained for motorsports and is able to track racing cars and motorbikes, with an option to home-in on riders' and drivers' helmets, if you wish.
We've not shot the two cameras alongside one another in challenging conditions but our initial impressions are that the R3's AF is a little bit better at sticking to subjects and also possibly a little faster, as befits its sports and wildlife focus. The faster readout of the sensor allows the R3 to update its AF calculations 60 times a second, which is more frequent than in the R5.
Eye Control AF
Beyond the differences in types of work the two cameras are designed to do, the biggest difference between the R5 and R3 is the presence of Eye Control AF in the R3.
The reintroduced Eye Control system is designed to be a genuinely intuitive way to very quickly position your autofocus point, to select a subject. It's especially well suited to the fast-moving subjects the R3 is designed to shoot, where saving fractions of a second in selecting a subject is more valuable than placing the AF point with great precision.
However, while this means it's far from essential for R5 users shooting landscape or product photos, it's a feature that might make the R3 a more attractive option for wedding photographers, where capturing a fleeting moment can be more important than providing the additional resolution the R5 offers.
Connection options
Another significant area of difference between the EOS R5 and R3 is the two camera's connection options, relative to one another. The R3 includes a number of additional options that speak to its very specific intended user-base.
So, while both cameras have built-in Wi-Fi that allows images to be transferred to a smartphone or home computer, the EOS R3 gains a multi-purpose connector in its hot shoe (pictured) that adds the option to connect a smartphone via a USB connection and take advantage of 5G connectivity. The larger camera also has a built-in Ethernet port for rapid image offloading when shooting on the sidelines of sporting events.
As we mentioned earlier, the multi-purpose hot shoe also allows the addition of an adaptor for connecting XLR microphones, further boosting the camera's video-shooting credentials.
Sadly, in both instances, the cameras are equipped with micro, type-D HDMI sockets, which are not the most rugged or reliable way to connect the cameras to external monitors, recorders or TVs.
Battery life
If you use the rear LCD, the R5 is rated as delivering a rather low 320 shots per charge, whereas the larger battery of the R3 is rated as delivering a downright impressive 760 shots per charge. As always, ratings derived from CIPA's standard test method tend to under-represent the number of shots you're likely to get in practice, but a rating of 760 shots will usually be more than sufficient for even the most intensive shooting session, a rating of 320 is more likely to see you run out of juice.
Bigger challenges come when you use the cameras' electronic viewfinders (and both have been designed to be as DSLR-like as possible, so we suspect you'll do so pretty often). In their 'smooth' modes, which give the most responsive view through the viewfinder, the figures drop dramatically. The R3 is rated as giving 440 shots per charge while the R5 promises just 220 shots, which are low-enough numbers that you'll need to have a second battery on-hand for the R3 and maybe consider buying a battery grip for the R5, especially for extended shoots.
These numbers improve considerably if you drop the cameras into battery-saving mode, but for fast action, most R3 shooters are going to need the camera's faster viewfinder refresh rate. So, whereas for some applications, R5 users can get their viewfinder rating up to 320 in power saving mode, R3 users are less likely to be able to use the mode that boosts the rating to a much more healthy 620 shots per charge.
Wrap-up
The R3 and R5, along with the launch of a range of high-end L-series lenses for the RF mount, make it clear that Canon expects the future of high-end photography to be mirrorless. Both are capable cameras and in most instances, the decision between them is primarily a question of what and how you shoot.
For an awful lot of applications, the R5's blend of speed and resolution will prove to be more than sufficient. But for fast-moving subjects, the R3 offers even faster shooting and greater battery life, even before you consider the added responsiveness that Eye Control AF offers. The R3 is also the better video rig, despite not being able to shoot 8K, simply because its oversampled 4K capture (up to 30p) shouldn't be limited by overheating, meaning it'll also be more reliable if you need to shoot both video and stills.
It's perhaps mainly wedding photographers who'll find themselves caught in two minds. An R5/R3 pair would let you deliver resolution for some shots and immediacy when you need it, but the cost of such a setup is considerable.
Depending on what and how you shoot, an R5 with a battery grip is likely to be the most sensible option for a lot of people: the EOS R3 is a more powerful camera with better performance, but it's also 50% more expensive. That said, once you've experienced Eye Control, you may choose to wait in hope of an EOS R5 Mk II with that feature added.
. dpreview.com2021-9-30 16:00
