An assembly for mounting and adjusting an instrument, the received or transmitted radiation of which must accurately hit its receptor or target, is provided. The assembly includes a base which is mounted to a wall or beam, a pedestal connected to the base and an instrument or instrument mount connected to the pedestal. The instrument may rotate with respect to the pedestal about a first axis defined by the longitudinal axis of the pedestal and about a second axis perpendicular to the first axis, and about a third axis perpendicular to the second axis. This enables the position of the instrument to be easily adjusted in order to enable the assembly to be used at various locations, and for different uses.