Matlab image centre, 3D points to pixel coordinates

Working on a code to simulate image triangulation i've found some troubles on how 3D points are mapped into 2D images in Matlab, so i wrote an easy example code to find out:

plot3(0,0,0,'marker','x'); 
set(gca, 'CameraPosition', [2 0 0],...       
        'PlotBoxAspectRatio',[1 1 1],...
        'CameraTarget', [0,0,0],...
        'CameraUpVector', [0,0,1],...                                             
        'DataAspectRatio', [1,1,1],...                     
        'CameraViewAngle', 50);   
axis on;    
grid on;
print -dpng -r100 test_img;

Since the camera has been moved only on X axis and it is pointing the axes origin i'm expecting the image centre to be [400 300], but it is not.

Why is the point [0 0 0] projected into [415 290]?

This is happening even with generic rotations and translations (image centre always at [415 290]) but that's not what i can read on computer vision books (as Zisserman for example) so i guess Matlab is taking something else into account when mapping 3D points into 2D.

Can anyone help me with that please?