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The new ASA AAF3/AAF4 is a high precision focuser with stepper motor and high-resolution magnetic absolute encoder.
It measures the actual focuser position directly on the inner focuser tube. It also contains a temperature sensor located in the focuser cable.

Due to the use of absolute Encoder and temperature compensation, your telescope will always be perfectly autofocused by the focuser.
The focuser has a USB interface and built-in WIFI (Software will be available later).


3“ Crayford
Drive – Rack and stepper motor
Carbon Housing
Absolute Encoder
10 kg Payload
1 Micron Accuracy
App Control (in planning – free update)
Temperature Compensation
12 Volt Operating Voltage
Flat Design – 74 mm Height
Focusing Hub 36mm
Weight 2 kg
ASCOM connection
2” Adapter
12V/1.5A Power Supply
4 m connection cable
1.8 m USB 2.0 cable
ACC Software

Installation & Configuration

Software installation
A USB flash drive is included in your focuser packaging. It contains USB drivers, the ASCOM platform installer, ACC focuser software and this manual as pdf.

  • Connect all the cables as described above
  • Windows 10 can install the necessary driver for the internal FTDI USB converter automatically via Windows update when you connect the focuser’s USB cable. If the driver installation does not work automatically please execute the file “CDM21218_Setup” on your USB flash drive. If the driver installation worked correctly, the focuser cable should be displayed in your Windows device manager in the section “Ports (COM & LPT)” as “USB Serial Port”. (the COM number might differ) It might be necessary to restart your computer after the driver installation.
  • If not already installed on your computer, install the ASCOM platform, by executing the file “ASCOMPlatformXX”
  • Install ACC by executing the file “ACCInstallXX” (if you have already installed an older version of ACC on your computer, uninstall it first)

Connecting ACC to other programs via ASCOM

If you want to use third party software just as FocusMax, MaximDL or others for focusing, you need to select “ASA ACC Focuser” in the ASCOM Focuser Chooser of your software.

AAF softw2.png


Using ACC focuser software

Start ACC by pressing the ACC desktop icon

1. Shows actual focuser position measured by absolute encoders
2. Visualization of focuser position
3. MoveAbsolute: Enter the desired position into the text field and press “GO!”. The focuser will move to this position.
4. MoveIncrements:
Enter the distance you want your focuser to move. Press “+” or “-“ to start movement.
5. MoveSpeed You can change the desired moving speed by actuating the slider bar. Start movement by pressing and holding “+” or “-“
6. Press “Stop” to stop the current movement
7. Connection status. If it shows “Device error” check all the cable connections.
8. Shows temperature. The sensor is located in the black box of the focuser cable.
9. Focuser status

If the focuser is forced to move in any direction, it compensates this undesired movement automatically.

Focus list Window

AAF use2.png
  • Here you can save various focus positions.
  • Enter the name of the position into the text field.
  • Enter the focus position into the text field or load the current position by pressing “Get”.
  • Press “Add” to save the position to your focus list.

You can move your focuser to certain positions by choosing a position from your focus list and press “Goto”.

Attach Wynne to the AAF3

There is no found documentation how to attach the Wynne to the AAF3. It is delivered with two adapters one dovetail extension to attach it to the OTA and a second focus extension with 3" opening without tread, so I concluded after tests that the extension without tread must be used and the red wheel with tread is not needed, see image below. The image shows the AAF3 and a Moravian G3 16200 camera with a Wynne camera adapter (red arrow).
One concerns the focuser inner diameter is a bit bigger than the Wynne so there is a small play, when lock down perhaps not a problem.

It should be possible to use the same camera-Wynne adapter as for the OK3Z.

One important thing I discovered, when you should push down the Wynne through the AAF3, with the new camera adapter, you first have to unscrew the 3 lock screws all the way out so nothing is in the way when the Wynne is put in place, that way the Wynne can go all the way to the bottom of the new camera adapter and the lock screws will NOT be applied to the Wynne corrector but instead on the camera adapter part. The screws are conical so I think they will have the effect of push the rim of the camera adapter towards the focus adapter bottom. In the image below the Wynne was stopped by the lock screws and did NOT go all the way to the bottom of the focuser extension (i.e. this is the wrong way to do it). We hope ASA support will make some instructions about this.

AAF3 Wynne.png