This adapter allows you to attach a C-Mount CCTV lens to your Altair Camera "BASIC" package.
The GPCAM already has a CS adapter but C-Mount lenses require an extra 5mm.
This adapter connects to the camera's CS adapter with built-in optical window.
Note: It has a 1.25" outer diameter which is the exact same diameter as a telescope eyepiece, allowing it to be used with a CCTV lens for telescope collimation in a similar way to the Takahashi Collimation scope. Very useful for adjusting the geometry of your Newtonian optics including focuser squaring and secondary offset adjustment and centering.