This command can be used to change your camera's field of view, the default is 60.
fov [desired fov]
|Desired FOV||Your desired FOV, the default FOV is 60.|
This command sets your FOV (field of view) to Subnautica's default - if you have not changed your FOV then this command will not affect your game.
This command sets your FOV (field of view) to 30 - a lower FOV means that your camera will be more zoomed in, so it is likely that ths will zoom your camera in (provided you have not changed your FOV before to a value lower than 30).