A visual back is the fitting at the rear of a telescope or focuser that holds a diagonal or eyepiece, either clamping a 1.25-inch or 2-inch barrel or threading onto an SCT, M68 or Maksutov rear thread. Choose by your telescope's thread and the barrel size you use: SCT owners can pick the Celestron SCT to 2-inch adapter or a Baader 2-inch ClickLock clamp sized for their tube, Maksutov owners the Antares M44.5 visual back, and focusers with M68, 2.7-inch, M60 or M56 threads the Baader Four-in-One Adapter. To complete the light path to the eyepiece, see Star Diagonals & Erecting Prisms.
