#17663 - 2-inch to 1-1/4" Compression Adapter with brass insert


In Stock: 8

The 2-inch to 1-1/4-inch Compression Adapter is our improved version of the #17662 1-1/4" adapter. This new version features a solid brass compression ring with machined grooves to hold 1-1/4" eyepieces firmly without slippage. A mere 1/8th turn of the upper locking ring tightens and loosens the 1-1/4" bore for easy use with gloved hands.

The #17663 offers a precision machined 2-inch outer diameter to fit into the drawtube of the TCF-S or TCF-Si focuser or any 2-inch focuser. A dovetail cut matches the three thumbscrews on the TCF-S while the 1-1/4" inner brass compression ring offers a non-marring alternative for 1-1/4" eyepieces and camera or instrument nosepieces. The adapter is self-centering for any 1-1/4" eyepiece or instrument nosepiece.

The 2-inch tube features an industry standard M48x0.6mm female thread for 2-inch screw-in type filters. Removing the lobed locking ring (shown in red) and the brass compression ring leaves a snug-fitting T-adapter with male M42x0.75mm threads.

Read Erik Wilcox's review of the #17663 Compression Adapter in the May/June 2010 issue of Astronomy Technology Today .

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 (locking ring): 2.20" (55.9mm)
  • Outside Diameter (main body): 1.995" (50.7mm)
  • Overall Height: 1.58" (40.2mm)
  • Clear Aperture: 1.25" (31.8mm)
  • Weight: 4.6 oz (130 g)
  • Back-focus Usage: 0.45" (11.5 mm)