#17666 - 2-inch to 3”x 24 tpi male threaded mount.


In Stock: 19

The 2-inch to 3-inch thread adapter was developed to easily adapt the Apogee and SBIG cameras and filters wheels for the TCF-S focuser.

By holding tight tolerances (+/- 0.003") Optec has achieved a slip-fit that is second-to-none. When used with the TCF-S focuser, the #17666 with its precision machined dovetail cut exactly matches the three thumbscrews on the focuser's drawtube. By tightening the thumbscrews, the dovetail is drawn tighter to the face of the drawtube completely eliminating flexure.

A word of caution, however, the FLI cameras and filter wheels featuring a 3-inch x 24tpi thread are slightly larger (3.005"). Be certain the #17666 2-inch nosepiece fits snugly into the FLI camera or filter wheel before installing into the TCF-S focuser. Additionally, the FLI filter wheels allow only 0.100" of thread to extend into the filter wheel body without obstructing the moving filter carousel.

Camera-side Compatibility:
  • TCF-S or TCF-Si focuser,
  • TCF-S3 or TCF-S3i focuser with #17804 3-inch to 2-inch reducer,
  • Any manufacturer's 2-inch focuser or receiver.
  • Overall Outside Diameter: 3.2" (81mm)
  • Outside Diameter (drawtube body): 1.995" (50.7mm)
  • Overall Height: 2.32" (59mm)
  • Height of 3x24 threads: 0.22" (5.6mm)
  • Clear Aperture: 1.80" (45.7mm)
  • Weight: 3.0 oz (85 g)
  • Back-focus Usage: 0.10" (2.75 mm)