Sony a7R IIIA vs Sony a5100

This is a full comparison between the cameras Sony a7R IIIA and Sony a5100. We compare them by looking at the categories you see below.

Sony a7R IIIA

Sony a5100

Manufacturing

These cameras are both manufactured by Sony.

Sony a7R IIIA were released 2021 and Sony a5100 was released 2014. That is a 7 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera	Released
Sony a7R IIIA	2021
Sony a5100	2014

Type of camera

Both these cameras are Mirrorless cameras. No difference there.

Sensors / crop factor

These cameras have different sensors. Sony a7R IIIA has a "Sony Full Frame"-sensor while Sony a5100 has a "Sony APS-C"-sensor, and their difference in sensors will also affect the crop factor and experience focal length. See the table below.

Camera	Focal length, 50mm f/1.8 **
Sony a7R IIIA	50 mm Full-frame sensor No crop factor/focal length multiplier
Sony a5100	75 mm Sony APS-C sensor Crop factor/focal length multiplier by * 1.5

** 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)

Resolution

Sony a7R IIIA has a 42 MP (Megapixels) resolution while Sony a5100 has 24 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
Sony a5100	24 MP 24000000 pixels 6000 x 4000

Sony a7R IIIA has a 76 % larger resolution than Sony a5100. 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

Sony a7R IIIA has a larger ISO-range than Sony a5100. Sony a7R IIIA has an ISO range that stretches from 100 to 32000 while Sony a5100 has 100 to 25600.

Camera	ISO Range
Sony a7R IIIA	100-32000
Sony a5100	100-25600

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.

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Sony a7R IIIA
Lens compatibility chart for Sony a5100

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 Sony a5100 can shoot up to 6 pictures per seconds.

Camera	FPS (Frames per second)
Sony a7R IIIA	10
Sony a5100	6

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 Sony a5100 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.

Sony a7R IIIA weighs 657 gr (equal to 1.45 lb) which is 132% heavier than Sony a5100 and its 283 gr (or 0.62 lb).

Camera	Weight
Sony a7R IIIA	657 gr 1.45 lb
Sony a5100	283 gr 0.62 lb