The Celestron T-Ring is compatible with Nikon F mount SLR and DSLR cameras. It allows you to attach a telescope or spotting scope to your camera so you can take short exposure images of terrestrial objects and celestial objects like the Moon.Attaching in the same way as a lens, the T-Ring has a sturdy bayonet flange to lock in place for secure contact.The telescope side of the T-Ring accepts a variety of camera adapters, including the Celestron T-Adapter or Tele-Extender. The T-Ring needs to be used in conjunction with the relevant T-Adapter for your telescope (sold separately).