Nikon D810 vs Nikon D3x

This is a full comparison between the cameras Nikon D810 and Nikon D3x. We compare them by looking at the categories you see below.

Manufacturing

These cameras are both manufactured by Nikon.

Type of camera

Both these cameras are DSLR cameras. No difference there.

Sensors / crop factor

Both these cameras have the same sorts of sensor (called "FX") 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.

** 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 (Nikon)

Resolution

Nikon D810 has a 36 MP (Megapixels) resolution while Nikon D3x has 24,5 MP. If we break down this in more detail this is the data behind the numbers:

Nikon D810 has a 48 % larger resolution than Nikon D3x. 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

Nikon D810 has a larger ISO-range than Nikon D3x. Nikon D810 has an ISO range that stretches from 64 to 12800 while Nikon D3x has 100 to 6400.

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 Nikon D810
Lens compatibility chart for Nikon D3x

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Nikon D810 can shoot up to 5 pictures per seconds and Nikon D3x can shoot up to 1-5 pictures per seconds.

Ability to record movies

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

Though, neither Nikon D810 or Nikon D3x can shoot movies so if that is a functionality that you are really looking for you should look elsewhere.

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.

Nikon D3x weighs 1260 gr (equal to 2,78 lb) which is 29% heavier than Nikon D810 and its 980 gr (or 2,16 lb).