Sony a7R IIIA vs Canon EOS R

This is a full comparison between the cameras Sony a7R IIIA and Canon EOS R. We compare them by looking at the categories you see below.

Sony a7R IIIA

Canon EOS R

Manufacturing

Sony a7R IIIA is manufacturered by Sony but Canon EOS R is from Canon. Both Sony and Canon are well known brands though.

Sony a7R IIIA were released 2021 and Canon EOS R was released 2018. That is a 3 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera	Released
Sony a7R IIIA	2021
Canon EOS R	2018

Type of camera

Both these cameras are Mirrorless cameras. No difference there.

Sensors / crop factor

Even though the camera sensors might be called differently they are both considered Full frame which means that the focal length of the lenses is not affected. There is no crop factor on any of these cameras and sensors.

Camera	Focal length, 50mm f/1.8 **
Sony a7R IIIA	50 mm Full-frame sensor No crop factor/focal length multiplier
Canon EOS R	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 (Sony)
Camera selection can affect the focal length (Canon)

Resolution

Sony a7R IIIA has a 42 MP (Megapixels) resolution while Canon EOS R has 30 MP. If we break down this in more detail this is the data behind the numbers:

Camera	Megapixels
Sony a7R IIIA	42 MP 42177408 pixels 7952 x 5304
Canon EOS R	30 MP 30105600 pixels 6720 x 4480

Sony a7R IIIA has a 40 % larger resolution than Canon EOS R. 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

Canon EOS R has a larger ISO-range than Sony a7R IIIA. Canon EOS R has an ISO range that stretches from 100 to 40000 while Sony a7R IIIA has 100 to 32000.

Camera	ISO Range
Sony a7R IIIA	100-32000
Canon EOS R	100-40000

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 R 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 Sony a7R IIIA
Lens compatibility chart for Canon EOS R

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Sony a7R IIIA can shoot up to 10 pictures per seconds and Canon EOS R can shoot up to 8 pictures per seconds.

Camera	FPS (Frames per second)
Sony a7R IIIA	10
Canon EOS R	8

Ability to record movies

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

In this case, both Sony a7R IIIA and Canon EOS R 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 R weighs 660 gr (equal to 1.46 lb) which is 0% heavier than Sony a7R IIIA and its 657 gr (or 1.45 lb).

Camera	Weight
Sony a7R IIIA	657 gr 1.45 lb
Canon EOS R	660 gr 1.46 lb