What controller do I need for the Starlight Instruments Posi Drive Motor?
The Posi Drive Motor System requires a separate controller for operation. It is designed to work with Starlight Instruments' Focuser Boss II or Electronic Focusing System (EFS). These controllers provide power, computer connectivity via ASCOM, and interpret data from the motor's integrated temperature sensor.
What is the benefit of the Posi Drive's timing belt system?
The timing belt creates a positive, physical engagement with the focuser's drive shaft, much like a chain on a bicycle. This completely eliminates the possibility of slippage that can occur with friction-based or pressure-based motor drives, especially with heavy imaging loads or when the telescope is pointed near the zenith.
How does the manual override on the PDMS motor work?
On compatible models like the PDMS-FTFF, the motor includes a built-in clutch mechanism. This allows you to turn the fine-focus knob on your Feather Touch focuser by hand to make small adjustments, without needing to loosen, disengage, or remove the motor itself. The motor's gearing simply slips until you stop turning the knob, then re-engages for electronic control.
Will the PDMS handle my heavy imaging train on a Celestron RASA 36cm?
Absolutely. The PDMS's lift capacity of over 56 pounds is specifically designed for instruments like the RASA 36cm that use large, heavy front-mounted imaging trains. The no-slip belt drive ensures the focuser position remains locked and repeatable, which is critical for maintaining collimation and focus on a fast optical system.
For a Takahashi FSQ-106EDX4, why choose the PDMS over the HSM motor?
While the Handy Stepper Motor (HSM) is an excellent choice for lighter setups, an FSQ-106 with a large-format cooled camera, 7-position filter wheel, and rotator can easily exceed the practical limits of a direct-drive motor. The Posi Drive Motor System (PDMS) is the recommended solution here, as its 56+ pound capacity and belt drive will prevent any focuser sag or shift, preserving the perfectly flat field of the Takahashi optics.
How does the built-in thermistor on the Posi Drive Motor improve my astrophotography?
The thermistor constantly measures the ambient temperature at the telescope. As the temperature drops overnight, your telescope's optical tube will contract, slightly changing the focal point. An ASCOM-compatible controller uses the data from the PDMS thermistor to make precise, periodic adjustments to the focus position, ensuring your images remain critically sharp over many hours without any manual effort.
