Sony a9 vs Sony a7S

This is a full comparison between the cameras Sony a9 and Sony a7S. We compare them by looking at the categories you see below.

Sony a9

Sony a7S

Manufacturing

These cameras are both manufactured by Sony.

Sony a9 were released 2017 and Sony a7S was released 2014. That is a 3 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera	Released
Sony a9	2017
Sony a7S	2014

Type of camera

Both these cameras are Mirrorless cameras. No difference there.

Sensors / crop factor

Both these cameras have the same sorts of sensor (called "Sony 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 **
Sony a9	50 mm Full-frame sensor No crop factor/focal length multiplier
Sony a7S	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)

Resolution

Sony a9 has a 24 MP (Megapixels) resolution while Sony a7S has 12 MP. If we break down this in more detail this is the data behind the numbers:

Camera	Megapixels
Sony a9	24 MP 24000000 pixels 6000 x 4000
Sony a7S	12 MP 12007680 pixels 4240 x 2832

Sony a9 has a 100 % larger resolution than Sony a7S. 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 a7S has a larger ISO-range than Sony a9. Sony a7S has an ISO range that stretches from 10 to 102400 while Sony a9 has 100 to 51200.

Camera	ISO Range
Sony a9	100-51200
Sony a7S	10-102400

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.

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Sony a9
Lens compatibility chart for Sony a7S

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Sony a9 can shoot up to 20 pictures per seconds and Sony a7S can shoot up to 5 pictures per seconds.

Camera	FPS (Frames per second)
Sony a9	20
Sony a7S	5

Ability to record movies

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

In this case, both Sony a9 and Sony a7S 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 a9 weighs 673 gr (equal to 1.48 lb) which is 38% heavier than Sony a7S and its 489 gr (or 1.08 lb).

Camera	Weight
Sony a9	673 gr 1.48 lb
Sony a7S	489 gr 1.08 lb