alainzu I am surprised by the big size of the prism and the inability to rotate or retract it.
In my case, the prism may shadow 1/4th oh the sensor field???
It would help somewhat if you rotate the OAG by 90 degrees so that the prism sticks down towards the long axis of the sensor.
I don't have this particular OAG, but pretty much all OAG comes with set screws, and sometimes, thumb screws that when loosen, allows the prism assembly to be retracted.
Chen
