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TCF-S Focuser

#17670 - Original TCF-S Focuser with USB/Serial control

Look at our TCF-Si or TCF-Lynx 2" focusers which have replaced the TCF-S.

Discontinued - Product no longer available for purchase

Like an old faithful dog, the day has finally come to say goodbye to the TCF-S focuser.  With thousands of these devices still in the field we have hestiated saying goodbye.  However, with the advances of the FocusLynx and new LSI controllers, it is time to retire the old, plastic box controller.  Optec will remain committed to providing service and is offering upgrade paths for new controller systems.  However, new TCF-S focuser will no longer be offered for sale.

The content below is maintained for current owners of the TCF-S. 

Original Sky & Telescope banner ad from March 2000.

Mechanically, the TCF-S is a robust Crayford style motorized focuser with high repeatability, no play and nearly zero backlash of only 0.0013 inch. Optec's implementation is ideal for applications which require exact focus such as CCD imaging or film astrophotography. A geared stepper motor rotates the drive shaft with one step rotation of the motor equal to a 0.000086 inch movement of the drawtube. The unit adds 3.5 inches to the telescope's back-focus as measured from the front to the end of the drawtube when at the mid-focus position. The total travel of the drawtube is 0.6 inches or 7000 steps. A pair of pushbuttons control the direction of focus and the DRO (digital read-out) displays the current position. The TCF-S focuser can easily handle cameras and instrument packages weighing up to 10 pounds. The TCF-S can be used by itself or with a PC for automatic focus with some of the popular camera control software.

  • Heavy-duty Crayford style 2" focuser
    Compensates for focal shift due to temperature
  • Supports instruments up to 10 pounds
  • Easy to use control box
  • Use with or without a PC
  • 4-digit readout for position
  • Simple Learn procedure for determing TC
  • Shut-off procedure remembers last position
  • Compatible with major camera control software for autofocus
  • Free control/interface program
  • Click here for further technical details


  • Weight Capacity:    10 lbs. (4.5 kg) minimum
  • Overall Height:  3.3" (83.8mm) fully IN to 3.9" (99mm) fully OUT
  • Focuser Travel:  0.6" (15.2mm)
  • Number of Steps:  7,000
  • Step Resolution:  2.2 microns
  • Weight:  2 lb. 8 oz. (1.1 kg)
  • Clear Aperture:  2" (52.8mm)
  • Back-focus Usage:  3.3" (83.8mm) to 3.9" (99mm)
How to Order:

Contact any Optec dealer, call Toll-Free 1-888-488-0381, email, or visit our ecommerce site: optecinc.us.

TCF-S Focuser Links: