Camera camera = newMapframe.Camera;
camera.X = -118.465;
camera.Y = 33.988;
camera.Scale = 30000;
newMapframe.SetCamera(camera);
Use the camera of the map frame. xy to center it, then scale it how you want. I should note this is for layouts. I don't know off the top of my head how it is done in the map view. Let me know if that is what you need and I can try and figure it out.