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Canon EOS R3 vs EOS 1D X Mark III

With the release of the latest professional full frame mirrorless EOS R camera we thought we’d compare key specs of the Canon EOS R3 vs EOS 1D X Mark III to see if it’s time to switch. We have sample images, discuss RF lenses, accessories, our own video review with so much to get excited about.

Canon EOS R3 vs EOS 1D X Mark III Specs and more

Old Skool vs New (DSLR vs Mirrorless)

The debate we sometimes hear about pros moving from DSLR to mirrorless has been going on for some time now. A handful of reasons stopping some working photographers from moving to newer mirrorless technology have been:

  • Availability of native pro RF lenses
  • Pro sized grip with intuitive handling
  • EVF blackout / refresh rate and overall quality against optical viewfinders
  • AF reliability
  • Robust build quality
  • Connectivity for file sharing
  • Battery life

Sample image news (reportage) with amazing detail

Sample Image 1: R3 with RF 24-70mm f/2.8 L IS USM at 59mm. 12 sec. f/5.6. ISO 100

The EOS R3 and EOS 1D X Mark III are the two high speed bodies aimed at professionals shooting sports, action, wildlife and news. Both are at the very pinnacle of their respective technologies, with DSLR’s having been around since 1987 and mirrorless since just 2018. But in 2020 Canon released the EOS R5 which revolutionised their mirrorless line-up by bringing a number of world first technologies into the hands of enthusiasts. Not least was the 8K and 4K 120p video capability alongside 8-stop combined IS. But the R5 isn’t aimed at high speed shooting, although it does address a number of concerns with mirrorless capabilities. Enter the new flagship EOS R3 to a drum roll please...

Sample 2 wildlife with 600mm RF lens

Sample Image 2: R3 with RF 600mm f/4L IS USM at 600mm. 1/2000 sec. f/4. ISO 100

EOS R3 shake down

With the release of the EOS R3 Canon is hoping to address all of the concerns pros have about switching to mirrorless, and then some. They are pitching the R3 as the definitive body, which can do everything the DSLR can. And do it bloody well too. Better than the shooter next to you using a DSLR. That means you’ll get the shot and you’ll get it first. So let’s compare specifications and see how they stack up on paper.

High speed frozen action sports golf shot

Sample Image 3: R3 with RF 15-35mm f/2.8L IS USM at 15mm. 1/66000 sec. f/2.8. ISO 1600

Canon EOS R3 vs EOS 1D X Mark III Specifications


Canon EOS R3 Mirrorless



36 x 24 mm CMOS Stacked, back-illuminated sensor

36 x 24 mm CMOS sensor


24 megapixels

20 megapixels




Shutter type / speed

Electronically controlled focal-plane shutter and Electronic shutter function in sensor

Mechanical: 30-1/8000 sec (1/2 or 1/3 stop increments), Bulb Electronic: 30-1/64000

Vertical-travel mechanical focal-plane shutter, electronically controlled at all speeds / Sensor Electronic shutter

30 - 1/8000 sec. (1/3 stop increments)

Continuous Shooting Mechanical / Electronic

Max. Approx. 12 fps. with Mechanical shutter / 1st curtain electronic speed maintained for 1000+ JPEG or 1000 RAW images.

30 FPS with electronic shutter speed maintained for 540 JPEG or 150 RAW images

Max. Approx. 16ps.

Max. 20fps in Live View mode with mirror locked up with exposure and AF tracking

(speed maintained for unlimited number of JPEGs or over 1000 RAW images)

ISO range

100-25600 (in 1/3-stop or whole stop increments). H: up to 102400

100-102400 (in 1/3-stop increments) ISO can be expanded to H1: 204800, H2: 409600, H3: 819200

Body IS

Up to 8-Stop


AF system

Dual Pixel CMOS AF II

Dual Pixel CMOS AF

TTL secondary image-forming phase-difference detection using AF-dedicated sensor

Auto AF Point Selection

1053 Available AF areas when automatically selected

191 point AF (inc face tracking and Eye AF)

Eye Control AF

YES. Select focus points or subjects to track simply by looking at them


Subject AF tracking

Humans, Animals (Dogs, Cats and Birds) or Vehicles (Racing cars or Motor bikes)


LCD screen

Fully articulated, 8.2cm, 4,200,000-dot touch screen

3.2" (8.01cm) TFT, approx. 2.1million dots


Blackout-free 5,760,000-dot electronic viewfinder with 120fps refresh rate and 100% coverage

Pentaprism Approx. 100%

Multi-Function accessory shoe



Movie resolutions

6K DCI / 60p RAW, 4K UHD / 120p

5.5k RAW, 4K RAW / 60p

Canon log

Yes, Canon Log 3

Yes, Canon Log 3

Connectivity, Computer, WiFi

SuperSpeed USB 3.2 Gen 2 USB C connector

Wireless LAN (IEEE802.11a/b/g/n/AC)

(5 GHz /2.4 GHz)12, with Bluetooth 5.0 support Features supported - EOS Utility, Smartphone, Upload to, Wireless printing

HDMI mini out (Type D, HDMI-CEC compatible), External Microphone In/Line In (Stereo mini jack), Headphone socket (Stereo mini jack), N3-type terminal (remote control terminal)

USB 3.1 Gen 2 (PTP) USB 3.1 Gen 2 (PTP)

Wireless LAN (IEEE802.11b/g/n) (2.4 GHz only), with Bluetooth support [5] Features supported – FTP/FTPS, EOS Utility, Smartphone.

HDMI (mini), External microphone (Stereo mini jack) Headphone Jack, RJ-45, N3 remote release terminal, Flash PC connector

Voice Memo



Battery / life

Rechargeable Li-ion Battery LP-E19 (supplied)

With LCD Approx. 860 shots

With Viewfinder Approx. 620 shots

Rechargeable Li-ion Battery LP-E19 (supplied), LP-E4N. 2,850 shots (viewfinder shooting) and 610 shots (Live View)

Storage type

1x CFexpress type B


2 x CFexpress 1.0 Type B

Weight Body Only

Approx. 822 g

Approx. 1250 g

The king is dead. Long live the king

So this is not every specification from these two heavyweights, (or lightweight in the case of the R3)! Rather these specs outline many of the main concerns with moving to the new mirrorless and we can see there is indeed a new king in virtually every respect. Canon has broken all of the boundaries and is showing professional users that it is indeed time to switch, or at least get ready to switch. (We’ll talk about lenses in a minute.) For now here’s a summary of how you can expect the EOS R3 to absolutely knock your socks off:

New motot racing subject tracking with helmet recognition

Sample Image 4: R3 with RF 100-500mm L IS USM at 500mm. 1/60 sec. f/22. ISO 100

  1. It has the first ever Canon developed Stacked, back-illuminated sensor. And it has a fast, very fast readout speed. You can wave goodbye to rolling shutter.
  2. It has a 20% higher resolution. Enough pixels while still being quick files to transfer.
  3. It can shoot faster at up to 1/64000 (see the sample image at this speed).
  4. It has a better LCD in every respect with full articulation and the EVF is blackout-free and has an absolutely blistering fast refresh rate with smooth panning capabilities.
  5. The EOS R3 will shoot at a blistering 30fps in electronic shutter mode. That is movie frame rate speed at 24MP and it sounds incredible when you hear it with no mirror slap, just raw power.
  6. The IS works incredibly well. You will be amazed that you can actually achieve 8-stops with the right lenses.
  7. Dual Pixel CMOS AF II brings about a host of advantages including speed, accuracy and new subject type tracking. It’s almost as though you don’t have to worry about focus, just your composition and the shot. It really is that good and works with motorsports helmets, bird eyes and more. What’s more you get 1053 Available AF areas when automatically selected with 100% sensor coverage, every pixel is covered.
  8. Eye control AF? AF based on where you are looking? Sounds like a gimmick right. Yes it does, but no it is not. The system is new, although Canon tried a similar approach before with the EOS 5 film camera, in 1992! Check it out here in the Canon museum. Eye control AF is actually incredibly effective and works by looking at your subject, then half depressing the shutter and bingo, the camera starts tracking. It works with all of the subjects the camera can handle, from motorsports to animals and humans. Welcome to the future of focusing and thank you Canon for a truly groundbreaking focusing idea.
  9. A multifunction accessory shoe sounds nice, but is it worth it? The short answer is yes. The new hot shoe on Canon cameras will allow you to add accessories which don’t need cables and don’t need batteries. Smaller, lighter and smarter. You can already get the new Speedlite Transmitter ST-E10, stereo microphone DM-E1D and shoe adapter AD-E1, with more accessories relatively soon no doubt.
  10. Video is becoming more prevalent for professionals to capture and both cameras offer excellent movie capabilities, with high quality in-camera RAW, but the EOS R3 wins again with 6K RAW and 4K 120p available without limit and without overheating.
  11. If you need to get your files off to the desk asap the EOS R3 wins hands down, with USB-C, 5G, and more inputs than you can shake a stick at. It is designed to get your files out as fast as possible and make your editor very happy indeed.
  12. One bit of very good news is that you can use your existing LP-E19 batteries, which will save a few quid when you upgrade. The downside is a significant hit on durability if you shoot mainly with optical viewfinder on the 1D X, which gets you 2,850 shots. That beautiful EVF uses some power, but we think you will grow to love it.

Pro RF lenses and what to do with your glass

Dart bubble burst ultra high speed

Sample Image 5: R3 with RF 70-200mm f/2.8L IS USM at 200mm. 1/66000 sec. f/5. ISO 512000

Firstly it is absolutely possible to shoot with your EF lenses. However you might well want to switch over relatively quickly. RF lenses are designed to work in unison with the stabilisation system, the AF system and are typically smaller and lighter while offering the same and often even better optical quality than their DSLR counterparts. You can get various converters to use existing EF lenses, including the following:

100 percent crop of water bubble burst

100% crop of image above. WOW!

In terms of native RF lenses, just about every pro focal length is now available from Canon. We have the holy trinity of f/2.8 lenses taking you from 15mm through to 200mm. There’s a pair of super telephoto primes with the RF 400mm f/2.8 and RF 600mm f/4, both of which work with the RF 1.4x and RF 2x extenders. Currently, Park Cameras have over 25 native full frame RF lenses and adapters including some beautiful specialist glass like the amazing RF 100mm f/2.8L Macro IS USM, the RF 85mm f/1.2L USM (and a defocus version), as well as a beautiful 50mm f/1.2 prime lens. Whatever your niche, however far away your subjects are, there is definitely a native lens available today.

Kingfisher photo sample EOS R3 with 100-500mm lens

Sample Image 6: R3 with RF 100-500mm L IS USM at 300mm. 1/5300 sec. f/7.1. ISO 5000

Video Review


Whether you are an existing Canon DSLR or EOS R mirrorless photographer working with high speed subjects, wildlife or simply want to shoot fast, there has never been a more compelling option available. Canon has really pulled out all of the stops with their recent mirrorless releases. Firstly the release of the R5 (and EOS R6) and now, this new high speed R3. The R3 is an almighty beast while remaining lightweight and of course bringing pro-level weather sealing. It has a built-in grip with familiar ergonomics, excellent build quality and it offers an upgrade in virtually every respect when compared to its DSLR counterpart.

100 percent crop of bird photo

Another 100% crop of the sample image above

Perhaps it really is time to think about switching or upgrading. Whatever you decide to do we hope you enjoyed this comparison and found it useful. If you want to convince yourself further, why not pop down to one of our stores and take any equipment for a test run so you can see just how good this camera and the RF lenses are first hand. We think you’ll be absolutely blown away.

We have some recent articles about some of the glass available for the full frame mirrorless system, why not take a peek:

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By Nick Dautlich on 14/09/2021

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