Screws onto the back of the telescope. With the Celestron T-adapters, 35 mm SLR cameras can be connected at the primary focus of the telescope. This allows you to take terrestrial photos as well as images of the Moon and planets. For deep-sky photography, an additional guide scope is required. In addition to the T-adapters, a T-ring specific to the camera is needed. Suitable for Schmidt-Cassegrain telescopes C5, C6, C8, C9, C11, and C14.