Charleston Lake
Imaging the Night Sky from Ontario Canada
Arduino Stepper Focuser
Automated Focuser - ASCOM compliant
When imaging, achieving correct focus is critical. Because there is no eyepiece to look through, focusing is achieved by viewing the CCD image on a monitor.

With the image data digitized by the CCD camera, focusing can be achieved automatically in software using V Curves (the bottom of the V curve is the sharpest focus). 

But... focusing can only be automated if there is a motor on the focuser assembly, that is linked back to the computer.

For this purpose, designed and built a focuser with a stepper motor, that uses an Arduino microcontroller as it's control base. The Arduino links back to the computer via USB.

The Arduino code was written to use the existing ASCOM standard protocol, allowing imaging software to add autofocusing to the sequence.

This allows fully automated re-focusing sequenced between integrations, to compensate for temperature related contraction of metal  and glass, which impacts focus.

Our focuser code is at present, basic, two speed, controlled either locally via manual pushbuttons or remotely via PC commands over USB. Design foundation is micro-stepping with accel/decel, to a A4988 based stepper driver. Additional features such as temperature offset, are planned.

Contact us if you have any questions related to this focus controller.
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