Canon EOS R3 vs Canon EOS 1D X Mark III

This is a full comparison between the cameras Canon EOS R3 and Canon EOS 1D X Mark III. We compare them by looking at the categories you see below.

Canon EOS R3

Canon EOS 1D X Mark III

Manufacturing

These cameras are both manufactured by Canon.

Canon EOS R3 were released 2021 and Canon EOS 1D X Mark III was released 2020. That is a 1 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera	Released
Canon EOS R3	2021
Canon EOS 1D X Mark III	2020

Type of camera

Canon EOS R3 is a Mirrorless camera while Canon EOS 1D X Mark III is a DSLR camera. More information about their differences will come soon.

Sensors / crop factor

Both these cameras have the same sorts of sensor (called "Canon Full Frame") which means that if you compare these cameras side by side the lenses will also have the same experienced focal length. Since both cameras have a Full frame sensor there will be no crop factor.

Camera	Focal length, 50mm f/1.8 **
Canon EOS R3	50 mm Full-frame sensor No crop factor/focal length multiplier
Canon EOS 1D X Mark III	50 mm Full-frame sensor No crop factor/focal length multiplier

** Experienced focal length when using a lens such as a common "50mm f/1.8"

Learn more about crop factor and focal length multiplier here:
Camera selection can affect the focal length (Canon)

Resolution

Canon EOS R3 has a 24 MP (Megapixels) resolution while Canon EOS 1D X Mark III has 20 MP. If we break down this in more detail this is the data behind the numbers:

Camera	Megapixels
Canon EOS R3	24 MP 24000000 pixels 6000 x 4000
Canon EOS 1D X Mark III	20 MP 19961856 pixels 5472 x 3648

Canon EOS R3 has a 20 % larger resolution than Canon EOS 1D X Mark III. This could give you more details in the picture but also a possibility to crop more in the pictures, afterward while editing the pictures, if needed that is.

ISO range

Both of these cameras offer the exact same ISO range. They both have 100 to 102400.

Camera	ISO Range
Canon EOS R3	100-102400
Canon EOS 1D X Mark III	100-102400

Autofocus and lens compatibility

Both of these cameras have a built-in autofocus motor. Some lenses, that support autofocus, do not have an autofocus motor of their own but this won't cause any problems with these two cameras.

Worth mentioning is that Canon EOS R3 belongs to the Canon EOS R-system and needs an adapter to work with Canons EF, EF-S, MP-E, and TS-E lenses. You can read more about this adapter here:
Canon Lens Mount Adapter EF-EOS R

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Canon EOS R3
Lens compatibility chart for Canon EOS 1D X Mark III

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Canon EOS R3 can shoot up to 30 pictures per seconds and Canon EOS 1D X Mark III can shoot up to 20 pictures per seconds.

Camera	FPS (Frames per second)
Canon EOS R3	30
Canon EOS 1D X Mark III	20

Ability to record movies

It is becoming more and more popular to record movies with digital cameras.

In this case, both Canon EOS R3 and Canon EOS 1D X Mark III can shoot movies.

Weight

The weight of the camera can be an extremely important factor, especially if the camera is about to be used, or carried around, for several hours at a time.

Canon EOS 1D X Mark III weighs 1440 gr (equal to 3.17 lb) which is 42% heavier than Canon EOS R3 and its 1015 gr (or 2.24 lb).

Camera	Weight
Canon EOS R3	1015 gr 2.24 lb
Canon EOS 1D X Mark III	1440 gr 3.17 lb