This is a bracket designed to mount a Canon EOS camera (tested with EOS500 and EOS550) onto a Celestron Nexstar 8SE mount using a Skywatcher 15cm dovetail plate, so you can do astrophotography with a standard camera. The bottom rear edge is aligned on a raised strip so that the camera can be removed and replaced with precise alignment. There is a slot at the right so that the battery compartment can be opened without removing the camera from the bracket.