ASCOM TCF-Si 2″ integrated focuser from OPTEC


ASCOM compliant 2″ integrated focuser TCF-Si

SharpLock ready!



ASCOM compliant TCF-Si 2″ Crayford focuser from OPTEC

Mechanically, the TCF-Si is a robust Crayford style motorized focuser with high repeatability, no play and nearly zero backlash of only 33 microns (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 2.2 microns (0.000086 inch) movement of the drawtube. The unit adds 89mm (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 15mm (0.6 inch), or 7000 steps.
In addition to having high resolution and low backlash from a purely mechanical standpoint, the TCF improves its focusing power with the addition of a temperature probe. This probe can monitor the temperature of the telescope tube and adjust focus to eliminate thermal focal shifts down to a resolution of 0.1° Celsius.
While the control box and DRO that come standard with the TCF-S focuser is a useful compromise between remote computer control and telescope-side hand control, this system may not be for everyone. Therefore, Optec has created an integrated variant: the TCF-Si. Unlike their predecessors, these focusers feature an integrated control board that allows direct connection between computer and focuser, thus eliminating the necessity of the external TCF-S control box and DRO.
The TCF-S is used  with a PC for automatic focus with some of the popular camera control software using the provided ASCOM compliant driver.
The TCF-S works very well with our SharpLock technology for real time auto-focus using the FocusLock windows application.

This order includes:

A 2” TCF-Si focuser, temperature sensor probe with 20” cable, 12VDC power supply with cord, 12-ft. Control cable, and 6-ft. USB/Serial cable.

The TCF-Si focuser series uses an OPTEC proprietary dovetail system (OPTEC 2400), they requires specific adapters for various telescope visual back.
Those are sold separately, visit the focuser product page to select and add to your card the one you would need for your scope.
If you have any question about adapter please feel free to contact us at Provide us with your telescope reference. Precisespart can make custom adapters for special needs and cases too.


Visit our support page for TCF-Si documentation, control software and driver.


  • Heavy-duty Crayford style 2″ focuser
  • Supports instruments up to 10 pounds
  • Easy to use control box
  • Use with a PC
  • Shut-off procedure remembers last position
  • Compatible with major camera control software for autofocus, as well as SharpLock
  • Free control/interface program


  • 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)


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Additional information

Weight 4 kg


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