A T-ring is a metal adapter with one end that fits on a lens mount and with the other end that connects to a T-adapter. Each camera brand has it’s own T-ring design. The T-adapter connects any T-ring to a telescope.
The Canon EOS T-ring shown in this setup is produced by Celestron. Some telescopes however, have threaded focusers that may accept a T-ring directly, thus, eliminating the need for a T-adapter.
Night Sky in Focus | Astronomy and Amateur Radio © Anthony Urbano | Manila, Philippines