Camera's center of rotation

I found a better solution :
You need to add to points (you can use arrows), these are your pivots.
So, you place those arrows in your component view (one for the camera and one for the turret). The direction is very important : to the camera/turret initial position.
Go to the event graph, on the mouse/stick update event you set the location on the camera equal to : pivot location + ( pivot forward vector × distance on the camera) and you set the pivot rotator equal to the camera rotator. That’s for the camera’s location. For the turret it’s easier, you just set the forward vector of the turret equal to the forward vector of the camera.