Resizing 3d window modifies the rendered image clip. This is not a professional way.
I know, that if it is important I do not resize the window and then I get always the same clip. But if it is resized by a mistake (misclick by mouse) then I have to render a whole group of pictures (for example if I made material options), because I will never find the original size of the window again. And making small differences on pictures coming one after another in the presentation makes them look very unprofessional.
So I suggest to lock the camera view cone rather to render settings. In Cinema4D it works great, so it is not geometrically impossible.
I hope I could help with this suggestion.