This is the William Optics Fluorostar 91 telescope mounted on the Orion EQ-G, with the ZWO ASI071MC Pro camera attached. Between the telescope and the camera is the William Optics 6AIII flattener / reducer. This telescope's aperture is 91mm, and the native focal length is 540mm, giving it a focal ratio of f/5.9. With the 6AIII, the effective focal length is 432mm and the focal ratio is f/4.7.