Autofocuser 2 WhiteCat FAQ

While testing our units, we carefully write down every issue that arises and solution to it - from basic connectivity, firmware upgrade to more complex problems like focuser slip and play. In result, this section composed from development and testing experiance, gathered from countless nights through years of astrophotography in field. Should you have additional questions not listed here, please let us know!

How do I assemble the AF2 WhiteCat autofocuser?

  • Mount the timing belt ring onto the backmost part of the helical focus ring. IMPORTANT: Tighten the 2 M3 belts just so the ring does not freely rotate on the helical focuser. We will tighten them further after the timing belt is mounted.
  • Mount the bracket onto the WhiteCat via 2 M4 bolts
  • Insert the stepper motor into the bracket and attach it to the bracket via 4 M3 bolts
  • Move the 3D printed pulley so that the pulley is in line with the ring.
  • Attach the timing belt. First slide it onto the WhiteCat and over the timing belt ring. Now attach it to the motor pulley first. After that slide it onto the ring of the helical focuser -> this can feel a bit tight but don't worry.
  • Connect the motor cable to the circuit and attaching the circuit shell to the back of the bracket via M3 bolt. Lock the circuit shell with M3 bolt.
  • Optional: mount the guide scope via 2 M3 bolts

What kind of power adapter can I use?

We recommend 12V DC power adapter, as the units are fine tuned to this specific voltage. Socket specification: tip positive, 5.5mm x 2.1mm. Should you not have 12V adapter at hand, the units should also work in range from 10V-15V without issues. Current output of the power adapter should be 1A minimum, but can be more (it will not damage the autofocuser).

When I connect the autofocuser to computer, Windows does not recognize it. What can I do?

You probably need to install the CH340 driver for Arduino compatible boards to provide USB connectivity. You can download it here or from authors website.

How can I upgrade focuser firmware?

Please refer to the firmware upgrade instructions.

How can I use the autofocuser on Linux/Mac OS/BSD

At the moment, only ASCOM driver is available. We are working hard on the INDI driver, stay tuned! :)

Focuser is recognized by Windows and virtual COM port is created. What now?

Next step is installation of ASCOM driver, so you can use the focuser with any of the automation programes, like SGPro. You can download the ASCOM driver here. You also need to install ASCOM platform.

I successfully installed new version of ASCOM driver, but now focuser will not connect. How can I fix it?

First check if you chose the correct COM port. If that does not work - ASCOM driver is developed for specific version of autofocuser firmware (specified in the readme file). We recommend you to always use latest firmware and latest ASCOM driver.

What ASCOM settings should I use?

We recommend you the following ASCOM settings for AF2 WhiteCat:

What SGPro settings should I use?

Backlash compensation By our experience, backlash compensation between 30 and 40 "IN" should suffice. Its best to test with Bahtinov mask to get the optimal setting for your WhiteCat.

I have changed the ASCOM settings but they have no effect, what can I do?

That happens if you change the settings while connected to the focuser. In order for ASCOM settings to have effect, you have to first disconnect from the autofocuser, change the settings and connect again.

Can I control the focuser manually?

AF2 comes with numerous ways of manual control, so you can focus with bahtinov mask or use it for visual observation without touching the focuser with your hands.

Wifi control

AF2 has the Wifi enabled by default in the Access Point mode. It enables you to manually control the autofocuser unit, without a physical remote controller and configure manual control parameters (which also apply to the Hand Controlled, explained in further sections of FAQ).

  • Connection - on your Wifi-enabled device (Phone, Laptop, Tablet, PC), look for "DSD-AF2_XXXXX" in the list of available networks. Connect to the network and enter the password (defaults to "AF2pwd123"). Password can be changed via AF2 Control Panel, explained in the further sections of FAQ.
  • Accessing UI - once successfully connected, open a web browser and navigate to If the UI is not opened and you are using a smartphone, it could have switched to the 3G due to lack of internet connectivity on the AF2 AP. Try disabling 3G data or turn the switching off.
  • Main UI - main UI consists of 3 sections
    • Header: contains current motor position and temperature (if the temperature sensor is connected)
    • Body: motor control - swipe left or right to move the motor for a preconfigured number of steps (fine/coarse)
    • Footer: fine/coarse selection and button to open the Settings UI
  • Settings UI - manual control configuration
    • Coarse steps: number of steps for coarse movement
    • Fine steps: number of steps for fine movement
    • Position: position override (when saved, the motor position is set to the entered position)
    • Reverse dir.: reverses the motor direction
    • Step mode: step size (1/4 or 1/8)
    • Speed mode: Low/Medium/High
    • Coils mode
      • Always on (recommended): coils are powered at all times
      • Idle - off: coils are turned off when focuser is not moving
      • Idle - coils timeout: coils are turned off after a specified amount of time from the last move
    • Idle - coils timeout (ms): timeout period for Coils mode "Idle - coils timeout (ms). After this period from last movement, coils turn off.
    • Current - move: current used for moving the motor. More current results in bigger torque. 75% is recommended.
    • Current - hold: current used for holding the position when motor is not moving (Coils mode "Always on"). More current results in bigger torque. 75% is recommended.

AF2 Control Panel

AF2 Control panel can be used for firmware upgrade, Wifi settings change or as manual control application. Once connected, you can configure the manual control settings (which also apply to the Hand Controlled, explained in further sections of FAQ) and move the motor in a variety of ways: fixed number of steps, 90/180 degrees, specific absolute position, continuous motion,...

Hand Controller

  • Connection - connect it to either of the 2 jack ports on the autofocuser unit.
  • Interface - 2 buttons, + and -.
  • Fine/Coarse movement - with a single press, the motor moves for a predefined number of steps in the current mode (fine/coarse). You can switch from fine to coarse by pressing both buttons at the same time and vice versa.
  • Continuous movement - you can move the motor continuously by pressing and holding + or - button.
  • Configuration - number of steps for fine/coarse movement, step size, motor speed, etc. can be configured via Wifi interface or via AF2 Control Panel.

What about temperature compensation?

AF2 comes with an option of temperature sensor. You can connect it to the either of the 2 jack plugs. Once connected, AF2 provides ASCOM/INDI with the temperature reading neccessary for the temperature compensation mode.

SGPro temperature compensation tutorial

  • In ASCOM settings, check "Temperature compensation" checkbox
  • Once connected to the AF2, you will be able to configure how often SGPro autofocuses in relation to the temperature change
  • After every finished frame, SGPro will check if refocus is neccessary. For example autofocus will be triggered, once the current frame is finished in this example (temperature differance from last autofocus is larger than 0.5 degree):
  • After autofocus procedure is finished, timestamp and temperature of last autofocus are updated.

Stepper motor is very noisy while holding position. What can I do?

Motor tends to release a bit annoying coils whinning noise while holding position. You can reduce the noise by setting holding current to 25%. But this reduces the holding torque, so do this at your own peril.

When focuser is turning, it causes vibration. What can I do about it?

Some amount of vibration is normal with stepper motors, included in our focusers. If you are using full step or half step mode, try to change it to 1/4 or 1/8 in ASCOM driver properties and increasing number of steps per change in SGP.

SGPro autofocus graph spike on right is causing smart focus to move away from in-focus position instead of towards. How can I fix this?

This can happen if you have any play in the focuser drawtube. Please check Settle buffer in ASCOM settings section.