#17668 - TCF-Si Integrated Temperature Compensating Focuser


In Stock: 4


17668 - TCF-Si Integrated Temperature Compensating Focuser, 2-inch motorized focuser.  Fully compatible with the original robotic TCF-S Temperature Compensating Focuser, the TCF-Si features an integrated control circuit with RJ12 socket for connection to any control computer.  

An 18-inch temperature probe can be attached directly to the telescope OTA to measure to current temperature and the integrated control circuit will compensate for the changing telescope focus.  Optec's USB/Serial cable makes the connection to any control computer while the TCF-S Commander software and ASCOM driver allows any higher level ASCOM software client to provide auto-focus.


  • Overall Height:    3.3" (84mm) to 3.9" (99mm)
  • Focuser Travel:    0.6" (15.2mm)
  • Focuser Midpoint:    3.6" (91.4mm)
  • Total Step Travel:    7,000 steps
  • Step Resolution:    2.2 microns
  • Weight:    2.2 lb. (1.0 kg)
  • Payload Capacity:    10-lbs. (4.5 kg)
  • Telescope-side Mount:    OPTEC-2400 dovetail
  • Camera-Side Mount:   2-inch drawtube
  • Control System:    Integrated TCF-S compatible circuit
  • Computer Control:   TCF-S Commander and ASCOM driver
  • TCF-Si Focuser
  • Temperature Probe with thermal tape
  • Optec USB/Serial cable
  • 12VDC power supply and wall cord


TCF-Si flyer

TCF-S Technical Manual


Specially designed for any SCT telescope including Celestron and Meade.  Compatible with any telescope with 84 to 99mm of available back-focus.  See our selection of OPTEC-2400 telescope adapters for most applications.  Custom adapters available upon request.

The TCF-S driver software is fully compatible with all ASCOM software packages including:

  • Maxim D/L
  • TheSky X (also compatible with native X2 drivers)
  • SGP
  • Prism
  • N.I.N.A.
  • any other Windows compatible ASCOM client.



Select any of our OPTEC-2400 2.4-inch dovetail telescope mounts for attachment to your telescope OTA.

Optional IN/OUT Remote Keypad, stock item 17680, allows manual push-button control while at the telescope. Ideal for visual use.


TCF-S focusers work with ASCOM, X2, and INDI software.